With its intricate clusters of interlocking crystals and silvery, metallic luster, stibnite is, not surprisingly, a favorite among mineral collectors. But stibnite is also interesting for its iridescence, tarnish and flexibility, as well as its prominently striated, and sometimes slightly curved, prisms.

Stibnite, or antimony trisulfide (Sb₂S₃), is the most abundant of the roughly 100 antimony-bearing minerals. Antimony’s chemical symbol (Sb) stems from stibium, the Latin word for stibnite. The origin of the word “antimony”, however, is uncertain. One possibility is the 15th-century Middle English word antimonie, which literally means “monk-killer”. This may be an allusion to the metal’s toxicity and the fact that many alchemists who had the misfortune to work with it were monks. Like antimony, stibnite is also toxic and precautions like hand washing should always be exercised after handling specimens.

Elemental antimony is dull, brittle, and silvery-gray to bluish-white in color. About as common as silver, it ranks 64th among the elements in crustal abundance. As a semimetal, it exhibits characteristics of both metals and nonmetals. In stibnite and other minerals, antimony forms metallic cations and weak metallic bonds.

Stibnite’s unusual crystal lattice structure explains many of its physical properties. Stibnite molecules, which have the shape of square-based pyramids, are arranged in layers within the lattice and joined by weak metallic bonding to create planes of perfect, one-directional cleavage. Weak metallic bonding explains both stibnite’s softness (Mohs 2) and low melting point of 1015°F (546°C)—low enough to fuse in a candle flame.

During crystal growth, stibnite’s planes of perfect, one-directional cleavage functions as “gliding” planes that account for its lengthwise striations and the slight curvature of its prisms. Because of physical and thermal stresses incurred during the growth process, this plane frequently displaces, or “glides”, causing subsequent crystal growth to proceed along new axes. Repeated displacement creates new crystal-face edges that appear as stibnite’s diagnostic, pronounced longitudinal striations. Displacement also generates lattice stresses that cause stibnite prisms to curve, an effect that is most noticeable in longer prisms.

Stibnite’s metallic luster is due to the weak metallic bonding between its molecular layers and the inability of its sulfur ions to completely shield its antimony ions. Metallic bonding creates a pool of free-moving electrons. The manner in which light interacts with these free electrons produces stibnite’s metallic luster. Like all minerals with a metallic luster, stibnite is opaque, meaning that it reflects, but does not transmit, light.

As an idiochromatic, or self-colored, mineral, stibnite’s silvery-gray color is caused by its essential elemental components and the nature of its crystal structure. Incident light striking the surface electrons is absorbed more or less equally across the visible spectrum. Light energizes these surface electrons, which return to their normal levels by releasing excess energy in wavelengths that we perceive as a neutral silvery-gray, with a subtle, but attractive, hint of blue.

This basic silvery-gray color is usually modified by tarnish and iridescence. Tarnish forms when microscopic particles of elemental antimony separate from the crystal lattice to create a thin film on the stibnite surface. Because of their disassociation from the pool of free-moving electrons, the metallic-bonding strength among these particles is decreased, and they reflect less light. Subsequently, the metallic luster is replaced by a dull, dark tarnish.

This microscopically thin tarnish also produces the phenomenon of optical interference and flashes of rainbowlike iridescence. Interference occurs when two or more light waves overlap. When incident light strikes tarnished stibnite, a portion is reflected from the tarnish film, while the remaining light penetrates the film and is reflected from the lower stibnite surface. When these two reflected light waves reinforce each other in frequency, phase and amplitude, the colors we perceive exhibit the vivid, “electric” character of iridescence.

Stibnite is a fascinating mineral, and intricate clusters of interlocking, silvery-gray crystals are among its many interesting features.

The post Studying Stibnite first appeared on Rock & Gem Magazine.

I am currently enjoying my artistic work with metal and stone. Like all artists, I have arrived at this place because of various life influences and artistic experiences. I certainly never thought I would be as busy as I am in retirement years, practicing my art and meeting people through social media who admire my work and are eager to purchase it.

I was born in the small, coastal town of Belfast, Maine, and as a child, spent the summers in Hampden, Maine. My mother, a seamstress, was an artist in her own way. I watched her create her own patterns and produce her masterwork. Today, I use patterns I have created to produce my jewelry.

My father introduced me to rocks and stones; consequently, rocks and fossils have always been a love of mine. I have picked them up all over the country. Dad was an earth-moving contractor who built roads and foundations. Our home was built in 1948 from pink granite brought from the coast of Maine. Today, our family home still stands as a restaurant in Hampden. On Sundays, my father took my siblings and me for long walks in the woods. We would sit on logs, enjoying the sunshine and the quietness. I loved watching the small creatures: frogs, dragonflies, butterflies, and all bugs. I admired the tiniest flowers. I realize that I now incorporate those elements into my jewelry.

My husband and I had a successful business for 25 years. We worked long hours and raised four children. All the while, I had to find moments to enjoy my artistic pursuits. I enjoyed sewing, painting, quilting, and basket weaving.

Meanwhile, I began to collect pottery. I always admired my family’s old pottery pieces. As I talked with potters and attended art shows, I had the desire to try this new medium. Pottery classes opened up a whole new world of clays and glazes. I worked hard to perfect the making of large bowls and vases, but realized the greatest satisfaction for me was in making smaller vases and bowls decorated with frogs, flowers and dragonflies. I thoroughly enjoyed experimentation and “working outside of the box”. I still display dozens of my pottery pieces in my home.

In 2004, I contracted Lyme disease. The joint pain and fatigue hindered me from continuing to throw pots on the pottery wheel, and necessitated a change in my artistic work. I began to experiment with stone carving; however, the Lyme disease prohibited me from doing heavy work with stone. For therapy, I also experimented and perfected skill in cloth weaving, making colorful wraps, shawls and scarves. Fortunately, over time and with proper medication, my Lyme disease was brought under control.

At about the same time, the local art center advertised classes to learn how to work with precious metal clay. As I considered yet another direction, I believed the precious metal clay work was, well, suited to me at that time. I was fortunate to have a talented teacher who trained me well. I began creating small, intricate silver pendants, rings and earrings. I shared my enthusiasm with others as I taught classes in Maine and Florida. It was gratifying to share my newfound craft and see what each student would complete. One day, an artist friend encouraged me to put color into my creations. That was magical advice that propelled me in a new and current direction.

I have found new satisfaction and joy in making silver jewelry with beautiful cabs. Because my friend suggested I use color, I discovered cabs made by Russ Kaniuth. I purchased some colorful stones and began to make butterflies and moths from my previous silver designs. It was so much fun!

As I work daily, I love to look at a cab and imagine what it can become. My customers have challenged me, asking for different critters such as seahorses, crabs, luna moths, owls, turtles, and bugs of all kinds. I have learned much about identifying various stones. I have favorite shapes and sizes, and two of my favorite stones are ocean jasper and flowering tube.

I now ship my jewelry all over the United States, and to Canada and other parts of the world. My husband, Sonny, travels daily to the post office. My heart is in each piece I create, giving each one a special personality, and my customers have expressed their surprise when they receive their beautifully wrapped packages.

Pictures of my pieces are posted on Instagram as Sonny and Ellen Cole. I hope you will enjoy viewing them.

The post Precious Metal Clay and Cabs first appeared on Rock & Gem Magazine.

Imagine that you are camping in a well-vegetated, high-mountain meadow in a remote area along the headwaters of the San Benito River, near California’s Diablo Mountains. When you awake in the morning, you notice a distinct white area on a nearby hillside that is glowing in the morning sun. Intrigued, you go over and walk up the slope. A white cavity glistens in the sun, and locked in the white material are small, oddly shaped, blue crystals that, at first glance, remind you of diamonds. The ground is littered with these same blue crystals.

This sounds like a fairytale, but it really happened to prospector Jonathan Mitchell Couch in 1907. Couch had been working in the nearby Coalinga oil fields, but wanted to go prospecting for mercury, which was needed in the nearby gold fields. He was grubstaked by R.W. Dallas.

Couch had chosen his prospecting area because mercury deposits had already been found in several places in California just before John Marshall picked up his nugget in Sutton’s millrace. Mercury was critical to gold recovery in the early days, as it would combine with small bits of gold, called “fines”, as an alloy, or amalgam, in a process known as amalgamation. The mercury could be boiled off and recaptured for future use, leaving behind its valuable golden load. Couch’s hope was to add to the dwindling supply of the slippery metal being mined in nearby Idria and New Idria.

Instead of mercury minerals, however, he stumbled upon these odd blue crystals, which he collected and brought back to town. Little did Couch realize that he had discovered what would one day become California’s state gem. Couch staked claims in his patron’s name, and the deposit was exploited as the Dallas Gem mine.

The blue crystals Couch had gathered ended up in a rock shop in San Francisco. Professor George Louderback, of the State Mining Bureau, saw the odd crystals and was intrigued by them. He eventually chemically identified the mineral as something new, a barium titanium silicate. When Couch brought Professor Louderback to the deposit, the professor pronounced the mineral “benitoite”, since it was found near the San Benito River and in San Benito County.

Other California deposits have reported occurrences of benitoite, but nothing found in Fresno, Kern or Mariposa counties comes close to the quality of the crystals found at the San Benito County mine.

Benitoite is unique in several ways, including its crystal form. Before benitoite, no mineral species had been found that belonged to the ditrigonal dipyramidal subclass of the hexagonal system, nor have any others been found since. The faces of benitoite crystals are usually triangular, and the overall form of the crystal is flattened, with facial modifications along the edges of the major faces.

Another unusual feature is its fluorescent response to shortwave excitation: a lovely, bright blue. The true color of benitoite is owed to what scientists call “charge transfer”. When light strikes the crystal surface, the energy is picked up by trace atoms of iron and titanium. Their electrons shift back and forth, or transfer, using oxygen as a conduit, or go-between. These outer electrons tend to absorb energy from the red end of the color spectrum, making wavelengths of the complementary color blue to become more dominant in the reflected light.

Benitoite crystals are often color zoned, with the richest shades near the crystal edges; the interiors of most benitoite crystals tend to be slightly less blue, sometimes almost gray, thanks to an included amphibole known as crossite. The bright-white material that caught Couch’s eye is natrolite, a fine-grained, crystalline, tectosilicate mineral species.

The mineralization of the deposit occurred millenia ago, in what was originally basaltic rock. This rock underwent extreme metamorphism, which turned it into crossite schist. This gray rock was later invaded by hydrothermal solutions, which deposited the benitoite, as well as the silicate minerals neptunite and joaquinite. Later solutions brought in the natrolite, which engulfed those species. The entire deposit is enclosed by the host rocks greenstone and serpentine.

Be aware that crossite is an amphibole altered from serpentine. Serpentine is one of the silicates in the asbestos group of minerals. To the federal government, “asbestos” is a dirty word, to say the least. The asbestiform crystal habit consists of long, fibrous crystals that, when inhaled, can cause mesothelioma and other lung diseases. This has caused the government to step in and regulate mining, and even recreation, in this area, which has seriously restricted the mining and digging for benitoite.

Benitoite is almost always found on crossite and enclosed by white natrolite, which has to be etched or dissolved away with acid to expose the benitoite crystals. The problem with using acid is that, if the etching is allowed to go on too long, the benitoite, neptunite and joaquinite crystals will become detached. Care must be taken, but the result is extremely attractive blue and black crystals contrasting nicely with the snow-white natrolite. The white natrolite ends up looking smooth in the extreme.

Neptunite is a fairly complex silicate containing potassium, iron, manganese, sodium, lithium and titanium. While blue gem benitoite is unique to the San Benito County deposit, neptunite is more common, and is found in other localities. It forms lovely, lustrous, prismatic monoclinic crystals with a square cross section. The crystals are usually sharp-edged and smooth, and appear black, but on thin edges they show an unusual reddish hue.

Tiny joaquinite crystals are sometimes associated with the benitoite and neptunite at this deposit. Its chemistry is even more complex than that of neptunite. It is a silicate made up of atoms of cerium, barium, sodium, iron, titanium, and the hydroxyl and hydrous radicals. Joaquinite’s problem is that it occurs in extremely small crystals, seldom over a couple of millimeters across, and seems to have formed in the natrolite. Any carelessness in etching the natrolite, and the joaquinite crystals are easily lost. These little, orange-brown crystals are usually randomly scattered within the rock, making it difficult to etch away the natrolite, while preserving the joaquinite. It is best done by someone who is experienced in specimen preparation.

Ownership of the property has changed repeatedly. As the financier of Couch’s prospecting expedition, R.W. Dallas took total control of the property and worked it until 1910. After that, it passed through the hands of several owners.

Josie Scripps, a member of one of the most powerful newspaper families in the country and a great devotee of minerals and specimen mining, owned the mine for a time. Josie also sponsored serious gem mining in some of the pegmatite mines in Baja California, Mexico. Other owners in relatively recent years were Bill Forrest and Buzz Gray. Buzz was a very active and exceptionally skilled gem faceter, and created many superb pieces of jewelry incorporating faceted benitoite. Another fellow who treasured fine benitoite and is well remembered by California collectors is Bob Gill, whose superbly fashioned benitoite necklace was displayed many times at California Federation shows and in Tucson.

The Kennecott Mining Co. drilled and sampled the property, much as they had with the red beryl mine in Utah, but without success. They were followed by the fellow who was so successful in mining rhodochrosite from the Sweet Home mine, near Alma, Colorado. Bryan Lees, of Collector’s Edge, bought the property and seriously worked it for several years, extracting specimens successfully.

Today, the official name of the deposit is the California State Gem mine, an appropriate name for the site of California’s official state gem.

It was the California Federation of Mineralogical Societies (CFMS), a large group of dedicated amateur collectors—aided by the parent American Federation of Mineralogical Societies (AFMS)—that developed the act submitted to the California Legislature to declare benitoite the state gem. The initial bill was acted on by the State Legislature in 1984, but failed to get enough votes. A year later, the bill was introduced again and passed.

Unfortunately, the state gem is mined in an area that is full of serpentine and related fibrous amphiboles. This fact gained the attention of environmentalists and the federal government because of fibrous minerals’ reputation for being a carcinogen when inhaled over time. A two-year study was initiated by the federal government to study the potential hazards of stirring up asbestos dust across the entire area. Mining, blasting, the use of heavy equipment, and heavy travel to the area were prohibited, as well as any serious mining for benitoite. These measures are still in place, but fortunately the mine is open to the general public as a fee-collecting site. Go to www.calstategemmine.com to get the necessary information for a field trip.

The post True Blue Benitoite first appeared on Rock & Gem Magazine.

Most collectors are familiar with the minerals gypsum and anhydrite. Both consist basically of calcium sulfate. The difference is that gypsum (CaSO₄·2H₂O) is a hydrous mineral with two attached molecules of water. Anhydrite, as its name implies, is an anhydrous mineral with no attached water molecules (CaSO₄).

Gypsum and anhydrite are textbook examples of how attached water molecules, called “water of hydration”, can affect such physical properties as crystal structure, density and hardness in minerals that have similar parental chemical compositions.

The asymmetrical configuration of water molecules, which consist of large, negatively charged oxygen ions covalently bonded to two small, positively charged hydrogen ions, explains their ability to attach to other molecules. Because the two hydrogen ions are grouped together, they retain a weak positive charge, while the opposite side of the water molecule, dominated by the large oxygen ion, retains a weak negative charge.

This atomic arrangement with its opposing charges enables water molecules to act as tiny dipole magnets that can attach themselves to other molecules through the attraction of hydrogen (polar) bonding. Hydrogen bonds form when the faintly positive poles of water molecules attract the negatively charged electrons of other atoms. The attached water molecules are electrically neutral and do not affect the electrical balance of the parent molecule.

In gypsum, the positive poles of water molecules are attracted to the slight negative charge of the oxygen ions in the sulfate radicals. Because hydrogen bonding is strongest at cold temperatures, gypsum becomes unstable when heat destroys its weak hydrogen bonds and drives off its water of hydration.

Whether calcium ions and sulfate ions will crystallize from aqueous solutions as gypsum or anhydrite depends primarily upon temperature, and to a lesser extent on pressure and chemistry. In low temperatures and the presence of available water, anhydrite can hydrate (or rehydrate) and convert to gypsum. Conversely, in higher temperatures and the absence of water, gypsum can dehydrate into anhydrite. Gypsum is by far the more abundant of these two minerals, because water and calcium-sulfate molecules have a stronger mutual attraction at ambient temperature and pressures.

While both gypsum and anhydrite are basically calcium sulfate, the presence or absence of water molecules makes a big difference in their physical properties. At Mohs 1.5-2.0, gypsum is much softer than anhydrite (Mohs 3.0-3.5). The reason is that gypsum’s attached water molecules increase the distance between its calcium ions and sulfate ions, weakening the strength of its ionic bonding. Increased inter-ionic distance also decreases density, so gypsum’s specific gravity is only 2.32, while that of anhydrite is substantially higher at 2.97.

Water of hydration also impacts crystal structure. Anhydrite crystallizes in the orthorhombic system, but gypsum crystallizes in the monoclinic system. And while anhydrite can hydrate into gypsum, gypsum can dehydrate into anhydrite. Therefore, these two minerals often form mutual pseudomorphs, with gypsum exhibiting the external orthorhombic shape of anhydrite and anhydrite exhibiting the external monoclinic shape of gypsum.

An interesting side-by-side example of these two forms of calcium sulfate is the blue angelite gem variety of massive anhydrite. It has a very fine grain, slight translucency, and a pleasing color caused by traces of divalent iron.

Angelite, which occurs as nodules in altered limestone, has been found only in Peru. When the anhydrite on the surface of angelite contacts groundwater, it hydrates and converts to gypsum, losing both its traces of iron and blue color. The result is a snow-white rind of soft gypsum surrounding a harder nodule of blue anhydrite.

The post Gypsum and Anhydrite first appeared on Rock & Gem Magazine.

OK, coprolites are funny. How could rock-hard dino doo, fossilized feces, silicified scat, petrified poo, not be funny? They are the quintessential bottom line of rockhound potty humor jokes. But coprolites are more than just the butt of jokes. They are invaluable windows into the lives of long-gone creatures.

Mary Anning was a pioneering paleontologist who lived in Lyme Regis, along the “Jurassic Coast” of southern England in the early 1800s. While excavating the fossilized remains of ichthyosaurs and plesiosaurs, she observed distinctive conical objects in the vicinity of the animals’ abdominal regions. These objects were commonly known as “bezoar stones”, stony, indigestible gastrointestinal masses that can’t be expelled. People assumed the Lyme Regis objects were modern-day bezoars. Upon further examination, Anning noted that the peculiar stones contained fossilized fish bones and scales, as well as the fossilized bones of other animals. Based on these observations, she theorized that they were not bezoar stones, but the fossilized excrement of the ichthyosaurs and plesiosaurs.

Around 1824, Anning discussed her theory with William Buckland, an eminent geologist of that time. After further study of his own, Buckland concurred that the stones were indeed fossilized feces. He named them coprolites, from the Greek kopros (dung) and lithos (stone), and in 1829, he presented his findings to the Geological Society of London.

Many coprolites have decidedly poopy shapes. One of the easiest ways to identify coprolites is to compare their shapes to modern analogues. The spiral pattern observed on modern shark excrement is similar to certain marine coprolites. Crocodilian coprolites look almost “fresh”. Caterpillar frass coprolites in amber/copal are often identical to their modern analogues, leaving little doubt as to their nature. Modern ghost shrimp pellets are strikingly similar to coprolites found around decapod fossils. So, in some cases, we can use shape as a factor for identification with some certainty.

Shape would seem to be the most obvious way to identify a coprolite, but paleontologists have learned that morphology is not always conclusive. There are at least three other factors to consider: composition (physical and chemical), geology/stratigraphy, and associated fossils.

Buckland studied fossils found in Kirkdale Cave, located in Kirkdale, North Yorkshire. The cave contained hyena fossils and the fossilized remains of various mammals with marks consistent with gnawing. There were also some white rocks that looked like dried dog doo. Buckland postulated that hyenas dragged animals into the cave, where they could eat them. He even kept a few hyenas at his home so he could compare their feces to the rocks from the cave. Chemical analysis confirmed his suspicions: the white rocks in Kirkdale Cave had essentially the same composition as the modern hyena droppings.

Just as Buckland learned from the chemical analysis of hyena droppings, paleontologists have found that coprolites usually contain a lot of calcium phosphate. This aspect of coprolites actually led to the commercial mining of them. In 1842, a large deposit was discovered in England and a new industry was formed to capitalize on the high phosphate content. The phosphate was extracted and used to produce fertilizer. It is sad to consider all of the specimens lost to the phosphate industry. By the 1880s, coprolite mining had waned, but demand during World War I briefly revived the industry because phosphate was a critical component of the explosives used in munitions. Who knew fossil poo had a hand in the First World War (www.cambridgeshirehistory.com)?

According to Dr. Karen Chin, University of Colorado, Boulder, phosphate helps facilitate the replacement of the original material with minerals. Carnivore excrement naturally contains a lot of calcium phosphate from the bones of the animals consumed. Herbivore excrement may not have much calcium phosphate, so other sources of phosphates and minerals are needed. That is one of the reasons more carnivore coprolites are found than herbivore specimens—the carnivore excrement has a better chance of fossilization. Therefore, paleontologists look for the presence of phosphate when determining whether a specimen is a coprolite or not (David B. Williams, www.earthmagazine.org).

However, fully mineralized fossils may not have any trace of phosphate left. Or, phosphate may be present, but there are no traces of ingested organic material such as bones, shells, fish scales, seeds, bark, grass, leaves, etc. In these cases, a specimen is less likely to be a coprolite. The animal had to have eaten something to have pooped something out. One would expect some trace of what it ate, even in a fully mineralized form.

Geology and environment contribute to fossilization. Fossils are typically preserved under sedimentary conditions. Other conditions have the potential to preserve specimens; for example, a very dry environment, extreme cold, tar and resin (amber). So sedimentation is not an absolute requirement, but it definitely helps.

If the geology of an area shows no indication of past sedimentary processes, it was probably not conducive to the formation of fossils, but even sedimentation can result in misleading shapes. Although fossils can be preserved within a concretion, non-fossil-bearing concretions occur in almost any shape imaginable, often being mistaken as fossils, and that can be problematic when trying to determine whether a specimen is a coprolite or not.

The stratigraphy of the area is important. The layer in which Anning found her fossils has been identified as Jurassic in age. Other ichthyosaurs and plesiosaurs have been identified as Jurassic age, so it makes sense that they could have been the source of the Lyme Regis coprolites. If a specimen is found in a layer whose age is wrong for the suspected pooper, then identification becomes more complicated. For example, what if you found what appears to be a vertebrate coprolite in a Precambrian layer (which would be before vertebrates were known to exist). The specimen would have to have been displaced from a later layer to that one; it may not be vertebrate, or it may not be a coprolite at all.

Associated fossils, specifically other fossils found in the same area, indicate the past presence of organisms and may be clues to the maker of the poo. Sometimes, coprolites are found near the fossilized remains of the animal that pooped it. Tiny pellets are found in area in Mississippi known for fossilized decapods. Without decapod fossils for reference, it would be difficult to recognize the pellets as coprolites.

Spiral coprolites similar to some modern shark excrement have been found with shark fossils, so they were likely deposited by sharks. Smaller spiral coprolites have been associated with various fish, as well. For Anning, it was the occurrence of curious stones in association with ichthyosaur and plesiosaur fossils that led her to the idea of coprolites.

The lack of associated fossils does not prove conclusively that a specimen is not a coprolite, but it is an important factor to consider. Because excrement is relatively soft compared to animal parts like shells, scales and bones, it is less likely to be preserved. Also, it is much easier for the excrement to be squished, eaten, or weathered away before there is a chance for fossilization to occur. Since the odds are more in favor of hard parts being preserved, the odds are also more in favor of one finding fossilized hard parts. Even if the area was a prehistoric potty, one would expect to find some bones, shells, or other fossils in the area.

Size in relation to associated fossils is another consideration. Some coprolites are so big that entire vertebrae of the hapless animal consumed by the pooping animal are preserved. Insect coprolites have been found preserved in amber and in petrified wood. Invertebrate fecal pellets may become the nucleus of sand grain-size glauconite nodules. Ostensibly, large coprolites were excreted by large animals and vice versa. Anning found the fossils of various animals of different sizes. The first coprolites she found were large, so a commensurately large creature, like an ichthyosaur or plesiosaur, would be a logical source.

Yet, as with other identifying factors, one must consider size carefully. Dr. Tony Martin, of Emory University, Georgia, explains that coprolites found in the Morrison Formation in Utah are composed of many small pellets. The coprolites are probably from sauropods, which were very large creatures. Because the excrement likely had a high fluid content, the pellets merged together rather than scattering individually. He compares this to modern mule deer, also very large creatures, who excrete tiny pellets (www.envs.emory.edu/). Had the pellets fossilized separately, other factors would become even more important in linking the tiny coprolites to their source.

Following the research of others is also a good way to determine whether a specimen is a coprolite. If someone else has examined all of the factors available and has identified coprolites with reasonable certainty, then there is a high probability that a similar specimen found in the same area is also a coprolite. Amateurs usually do not have access to all of the diagnostic tools that a researcher or other professional has, so why not rely on their expertise?

If a specimen fails more tests than it passes, the odds are it is not a coprolite. One might argue that the composition of a specimen might not include phosphate or organic traces because the original poop has long since been replaced by other minerals. If some structure is still discernible, even in a mineralized form, then the specimen could still be a coprolite. But if all that is left is merely a cast of the original object, it is simply that: a cast. Just as one would consider the cast of a shell a trace fossil and not a fossilized shell, the cast of a coprolite would be a trace fossil, too; essentially, it would be a trace of a trace.

Consider an extraordinary copal specimen found near Mombasa, Kenya, along with some vertebrate fossils. Apparently, some feces was covered quickly by sediment, subsequent erosion revealed a void where the feces was, then resin filled the void and formed copal. Is the copal a coprolite? Most people would agree it is a cast and not a coprolite. Not that a cast of prehistoric poop would not be of any interest. It would still have significance, but without some indication of the original composition of the poop, its value as a scientific aid would be reduced to external morphology and associated fossils only. And without associated fossils, only the morphology would be of any value.

There is an ongoing debate about specimens from Salmon Creek in Washington. These specimens are composed of siderite. There is no phosphate, no organic traces, and no associated fossils. However, these specimens exhibit the most interesting aspect of coprolites—superb shape. They look like they were just pooped; so much so that their shape alone has convinced many people they are indeed true coprolites. Some specimens even have longitudinal striations that resemble markings made during excretion. Conversely, many people believe they are pseudofossils. There are equally convincing arguments from both sides of the debate.

Adolf Seilacher, a German paleontologist who has contributed significantly to ichnology (the study of trace fossils), along with Cynthia Marshall, H. Catherine W. Skinner, and Takanobu Tsuihiji, offer an explanation of the Salmon Creek specimens. “A fresh look at sideritic ‘coprolites’” was published in the journal Paleobiology (Winter 2001). Seilacher, et al. describe the specimens as “cololites” (feces preserved while still inside the animal’s gastrointestinal tract) that were “prefossilized [sic] by bacterial activity and later transformed into siderite with no traces of original food particles left.”

The authors also address the lack of other fossilized remains: “All occurrences are found within fluvial overbank deposits that carry no other vertebrate remains. Their absence could be due to aquifer roll-fronts that destroyed phosphatic bones and teeth but favored siderite precipitation.” Rather than excretion marks, longitudinal striations would be indicative of colon structure.

In the article “Enigmatic origin of ferruginous ‘coprolites’: Evidence from the Miocene Wilkes Formation, southwestern Washington” (Geological Society of America Bulletin, 2001), George Mustoe examines the controversial Salmon Creek specimens. In four hypotheses presented in the article, he cites the work of other paleontologists who studied similar formations where material was extruded in various ways: “coseismic liquefaction”, where material is forced up through cracks in rocks or sediment; “expulsion of sediment in response to gravity”, where material is forced down through cracks in rocks or sediment; intrusion through hollow logs, aka the “knot hole theory”; and methanogenesis, where methane gas released by decomposing organic matter has geologically “burped” the siderite into the coprolitic shapes. Mustoe concluded they are “pseudocoprolites produced by mechanical deformation of iron-rich sediment”.

Perhaps referring to the passionate views on both side of the controversy, Mustoe added, “However, the origin of these specimens remains clouded in mystery, and our best hope for arriving at a definitive explanation will come if researchers combine their search for new evidence with an open mind.”

Whether you consider Salmon Creek specimens to be coprolites or cololites or neither, there are undisputed examples of pseudocoprolites. Concretions of various compositions can have decidedly poopy shapes. Some botryoidal minerals, like hematite and goethite, can be mistaken for coprolites. Snakeskin agate may have the shape and crackled look of a coprolite, too. I even have some extruded plaster that fell a short distance and hardened into a perfect pseudocoprolite specimen.

So you think you’ve found a coprolite or you’ve purchased a specimen sold as a coprolite. Is it truly a coprolite? Unless you are a serious researcher or simply a purist, does it really matter? If you like it, enjoy it. Coprolites are fun. They are perfect for capturing a third grader’s attention, and they can even be incorporated into jewelry or carved and polished. Plus, there is much that can be learned from coprolites.

By studying the physical composition of coprolites, paleontologists can deduce whether the animal that produced it was most likely a carnivore, herbivore or omnivore. Traces of organic particles can help researchers determine what an animal ingested, which in turn helps determine where and when the animal lived. Seeds, spores, pollen, wood, grass, leaves, even microorganisms and parasites, can be preserved within a coprolite. Anning learned from bones she found in coprolites that ichthyosaurs had eaten other ichthyosaurs. She also found fish bones and scales, as well as belemnite remains in the coprolites that helped confirm ichthyosaurs were aquatic creatures.

If a coprolite can be linked to a potential pooper, the shape of the coprolite may provide clues to the contours of the internal structure of the digestive system of the animal. Shark coprolites and some fish coprolites are a good example of this. Buckland wondered if spiral ichthyosaur specimens were an indication that their intestines had spiral ridges. Without living ichthyosaurs to use for comparison, he injected cement into modern shark intestines. The shape of the resulting casts was similar to the ichthyosaur fossils. Because some of the ichthyosaur specimens Anning found were actually cololites and were preserved internally rather than being excreted, the experiment showed that ichthyosaurs probably did have spiral valves in their intestines, much like modern sharks (Gary L. Stringer and Lorin King, “Late Eocene Shark Coprolites from the Yazoo Clay in Northeastern Louisiana”, New Mexico Museum of Natural History and Science, 2012).

Conversely, coprolites with no shape can still provide helpful information about an animal. An amorphous coprolite could be indicative of a long fall ending in a splat or it could point to a high fluid content in the original feces that prevented a distinct shape, as in the sauropod coprolites from Utah. A lack of shape might be caused by trampling, decay, weathering, or even insects dining upon the fresh feces. Fish coprolites from the Lower Carboniferous Wardie Shales near Edinburgh, Scotland, are often found inside ironstone concretions that must be cut open to reveal the coprolite. The distinctive cracks around the specimens give them the appearance of squashed bugs, hence their nickname, “beetle stones”. The concretions obscure the shape of the coprolites, but the value of the coprolites is not diminished by their lack of original shape.

Despite the value of coprolites to paleontologists, many people are unaware that fossilized poop exists, and are surprised when they learn about it. But even people who are familiar with coprolites have never heard of related fossils that are important, too. Coprolites are just one of several trace fossils called bromalites, a term that encompasses fossilized material that came from the digestive system of an organism.

In addition to cololites, another bromalite preserved while still within the organism is a gastrolite (fossilized stomach contents). Gastrolites are not to be confused with gastroliths, also called “gizzard stones”, which are indigestible stones that were either swallowed by accident or were swallowed on purpose for ballast or to help crush food.

Regurgitalites (also regurgaliths) are fossilized vomit. Like gastrolites, regurgitalites contain food that was not fully digested. So, gastrolites and regurgitalites have components that are more easily identified, as well as components that are mostly intact. They are immensely helpful in determining what the organism ate.

It is important to note that, unlike regurgitalites and coprolites that, by definition, have exited the organism, gastrolites and cololites are more likely to be found in or near the organism. This makes associating the trace with the organism eminently possible and subsequently invaluable for research.

Another recently recognized and understandably rare bromalite is a urolite, a trace fossil caused by urination. Urolites are not fossilized urine, but soil deformations caused by urine hitting the ground. They are preserved in sediment the same way footprints and other track fossils are preserved.

So, in the fascinating study of trace fossils, coprolites and their kin may elicit some giggles, grins and groans, but they are also an intriguing piece of a paleontological puzzle for which we have tantalizingly few pieces.

The post Coprolites first appeared on Rock & Gem Magazine.

Here’s the scenario: You are into the first day of a two-day society show. One of your members is asked to drive his or her car on behalf of your society (e.g. moving supplies, doing errands, making coffee runs, etc.) and, while operating their vehicle, is involved in an accident and gets sued.

Clearly, the driver needs to have adequate limits of liability coverage under his or her own car insurance policy (since the California Federation’s policy does not extend any coverage to the owner or operator of a vehicle). But who else is likely to be sued?

Correct: your society and its members (just like an employer who gets sued because an employee is involved in an auto accident while on company time). Does your society have liability protection for such an accident and resultant lawsuit?

Well, maybe. If the rock and mineral society is not a member of the California Federation, then probably not, unless the society has gone out into the insurance market and purchased such insurance. However, if the rock and gem club is a member of the California Federation, then yes! Experienced defense attorneys and $1 million of liability coverage would provide for the cost of legal defense of the society and its members under a benefit called Non-Owned Auto and Hired Auto Coverage. Neither the society nor its members would have to pay a lawyer to defend themselves (win or lose!), let alone the huge problem that would result if the Society was ordered to pay monetary damages!

Just think of those rock and mineral societies that go it alone, without belonging to the Federation. It’s very likely that they may find themselves without this valuable coverage! This said, make certain that your society keeps its dues paid on time! This insurance coverage—and more—is paid for through our annual member dues.

As our societies and clubs plan for their annual shows, remember that most venues will require proof that the society has liability insurance to protect the building owner in the event that there is damage to the building or that someone is seriously injured while on the owner’s property. As long as the society is a member in good standing of the California Federation, the society can obtain this proof of insurance. Furthermore, if the function does not involve more than 500 participants or attendees, there is no charge whatsoever for having McDaniel Insurance Services issue such proof of insurance documents. A very nice benefit to us!

When you need to provide such proof of insurance you can find the forms on our Federation’s website, www.cfmsinc.org. To avoid a charge for an expedited certificate, please allow plenty of time in advance of your event!

Outside of California, check with your regional federation to see what insurance options it offers.

The post Are You Insured? first appeared on Rock & Gem Magazine.

For years, I had been seeing cabochons and rough called “Detroit agate” or “fordite”. They are extremely colorful, and they make fabulously colored and patterned pieces that can be set in jewelry. I was hooked. I decided to try making some.

Fordite is not a stone, but a manmade material that came out of the assembly lines of the Ford Motor Co. The process that created fordite is no longer in use. In the old days, cars were painted using hand-operated spray guns, and the overspray adhered to the racks, which were then run through the ovens with the cars. (Today, the paint is electrostatically magnetized to adhere to the car bodies, leaving no overspray to accumulate in the painting bays.) Many repetitions resulted in tens or hundreds of layers of oven-hardened paint. When the buildup got in the way, it was chipped off.

It seems a few workers saw the potential for using these chips in creative pursuits. They found the fordite could easily be shaped and polished and could be used in many artistic applications. Jewelry made from fordite is often fabulously patterned and colored, but is susceptible to scratching if exposed to a harsh environment. A few of the old pieces are primarily black or brown, as most cars were painted these colors in the late 1940s. The colorful lacquers from the 1960s and the very bright acrylic colors from the late 1980s produce the more interesting stones, at least according to my taste.

One of my best friends from college is a retired Ford Motor Co. vice president. He was very instrumental in the paint area evolution at Ford. While he was going to college, he worked on the production line full-time at the local plant. His actual middle name is Ford. While we were in college in the late ’60s, I introduced him to the sister of another of my old friends. They hit it off and have been married ever since.

Creating a few pieces of jewelry for them using fordite, inspired by his Ford Motor Co. association, seemed a natural way to get into using this material creatively and exploring how to cut it.

The first step for me was to purchase some rough. I went to eBay, searched for “fordite”, and purchased three pieces for a whopping $9.95, plus $4.95 shipping. When they arrived, I was pleased with the colors and patterns.

I thought about what jewelry I might make. The susceptibility to scratches led me to decide on a tiepin for him and a pendant for her. I wanted something that screamed “Ford!” to be part of his piece, so I did an online search for Ford memorabilia and found a tiepin that was from Philco Ford, an old subsidiary. I decided the fordite cabochon could simply be shaped to overlay the half of the tiepin with the word “Philco”, leaving the distinct blue-and-silver Ford logo. For the pendant, I decided I didn’t need to tie it as closely to Ford—after all she didn’t work there, he did.

I went to Etsy.com and searched for fordite and found Susan Hamby (a.k.a. suzybones), who was selling cabochons. The cabochons were delightful and extremely colorful. I purchased a stone that I felt would make a lovely pendant for a reasonable $31.99, plus $2.99 shipping.

I asked Susan what process she used in creating the fordite cabs and got this reply:

“Cut [the] blank with [a] bandsaw. I use a Genie to grind and sand to 600 grit. Then wet sand over the sink to 1500 grit. Then spray with automotive clear coat. This is for the base coat material (from the ’80s). For lacquer (from the ’60s) the process is similar, but instead of clear coat I buff to gloss with rubbing compound on a medium felt wheel. Keep your heat low.”

I did a search to see what process other people were using to sand and polish the stones. These are some of the recommendations I found on blogs:

“Hit it with Zam™ on a buffer wheel.”

“It’s very cool stuff to work with, and from what I have seen, you will often have to throw out the standard dome shape and instead go with a basically flat top with some variance in thickness.”

(Note: The layers are so thin you get very little pattern at an angle; a flat top is almost mandatory.)

“I just recently worked my first piece of [Minnesota fordite]. First, I was very surprised how lightweight it was. I started it on a Genie 280 and quickly moved it along the Nova wheels ending on the 14000. I finished it with Zam on a Dremel.”

“I used a compound called ‘Varnax’ when polishing and it worked very well.”

“I consulted with an auto paint supplier … he recommended Meguiars mirror glaze #2 ‘fine cut cleaner’ to polish the fordite. It creates a nice polish even using a damp paper towel … and by hand.”

For the tiepin, I needed a 6 mm by 22 mm cabochon. I selected one of the three slabs and marked off a rectangle a few millimeters larger than required. I sawed it out on my band saw. I also cut one on my diamond trim saw just to see how that worked. I preferred the diamond saw, but the band saw worked well, too.

I proceeded to cut two cabochons on the Diamond Pacific Genie. I started with the 220 grit hard wheel, but because I am not overly patient, I dropped back one wheel to a 60 grit cross-hatch to do the rough grinding. Then I moved to the 220 grit hard wheel, and then the 280, 600, 1200 and 3000 grit soft wheels. I then polished with Zam on a muslin buff on my jewelry buffer. The finish was terrific. The material I was cutting was very solid—no pits or crumbling—so it worked about like variscite.

Now that the tiepin was complete, it was time to create a finding for the pendant cab I had purchased from suzybones. To start, I traced the outline of the cab onto paper. I then drew a bail and prongs on the outline. I glued the drawing to a sheet of 24 gauge sterling silver sheet using rubber cement. I cut the pendant from the pattern using a jeweler’s saw with a 3.0 blade. Once the blank was cut out, I filed the edges smooth and sanded all over it with superfine, ultrafine and microfine sandpaper. Then I took it to the buff and polished it with Tripoli, washed it with soap and water, and polished again with rouge.

I bent the prongs gently into place around the cab and strung the finished piece on the chain. I was very happy with my fordite tiepin and pendant.

Fordite Care

I learned about fordite care from Cindy Dempsey at Urban Relic Design (www.urbanrelicdesign.com).

“Fordite comes in different varieties that have somewhat different tolerances and strengths. It is inherently rather fragile to begin with, so it should be treated with care. You might compare it in that regard to a pearl. Fordite has a soft to medium surface hardness, and it will take a nice glassy polish.

“General cleaning can be accomplished with warm soapy water. However, like other softer materials used in jewelry, fordite may pick up tiny, light scratches with frequent wear. The quick solution? Using a fine car polishing compound like Turtle Wax®, and buffing to a high shine with a soft, 100% cotton cloth, or just green jewelers rouge. This will revive the luster in a well-worn piece without damaging the pattern.

“Fordite jewelry set in silver should be cleaned with a silver polishing cloth. [S]ilver dips are not recommended, as they may interact with the enamel and discolor the metal.

“All of the fordite cabochons and beads that we use in our finished jewelry have been put through a preliminary ultrasonic stress test to ensure good surface tension and adhesion of enamel layers. If any of the finished cabs or beads show structural weakness, or delamination, they do not pass our test and are rejected for use in our jewelry.

“However, please note that using an ultrasonic jewelry cleaner to clean fordite jewelry is not recommended. Arbitrary time spent in an ultrasonic cleaner could be damaging to even the most hearty pieces. You opal and pearl fans know what I mean … .”

The post Working with Fordite first appeared on Rock & Gem Magazine.

Indonesian fossil palm root is a stone of such beauty, with its high-contrasting earthy tones against a stark black sky. Many lapidaries who cab this material try to capture what is seen most, a fire rising up in the midnight sky.

This material is not very common in the marketplace; it seems to be rather scarce, so when you do find some at a rock show or posted for sale online, my suggestion is to pick it up as quickly as possible! If you want to see some really fine examples of cabochons made from this material, go look at cabochon artist Lexx Stones’ website, www.lexxstones.com.

Making cabochons with this material is great for lapidaries of all levels. It has a hardness of approximately Mohs 6, it is easy to design with, and it cuts and shapes rather nicely, without much fuss. The only real pitfall with this material is that the very outer edge can be porous and softer than the rest of the piece, so a suggestion would be to start your designs at least 3 mm and up to 5 mm in from the edge to ensure that you will get a clean cut without pitted or cracked-off edges.

Cutting slabs from rough material may be a little tricky. It’s almost always in very odd shapes, so wedges and caution should be used when locking down the stock into your saw. Make sure it’s well secured in the vice by grabbing hold of it and yanking in several directions to find out if it will budge.

This is the type of material that you really don’t want to cut very thick, so I set my cuts to 5.5 mm up to 6 mm. One reason is to preserve as much of it as I can to obtain the most slabs I can get from the rough. The other reason is that I may want to consider forming a slightly lower dome than usual.

When cabbing Indonesian fossil palm root, remember that it’s a natural material and the patterns will change drastically within a distance of 1 mm. When deciding on where to lay out your preform, always keep in mind that the pattern you see may not be what you end up with. It will most definitely change as you start doming the top of your cab. For those who like to cab flat tops, this obviously won’t be an issue—what you see is what you will get!

Once your preforms are ready to start grinding your shape and doming the top, dry your cab well and inspect it for any pits or cracked edges, most of which will be within the golden-brown areas. You may need to stabilize these areas or adjust your pattern around them. I usually spend a little extra time smoothing the final shape on the 220 grit steel wheel. Doing this leaves less chance of undercutting in the lighter-colored areas that may be slightly softer than the black regions. After that, the cabbing process should be a breeze.

Most lapidaries usually stop at 14,000 grit, which still leaves this material looking extremely nice; however, if you can go to 50,000, it will surely leave you with a gorgeous mirror finish. Indonesian fossil palm root shines up as nicely as many jaspers would, and in most cases, no extra polishing compounds will be needed to obtain a really nice cab. If you wish to use compounds such as cerium oxide, be sure to fill any pits—especially if they are in the black areas—ahead of time, or the compound with fill that void and create an eyesore.

The post Indonesian Fossil Palm Root first appeared on Rock & Gem Magazine.

In recent years, rock shops and dealers at gem and mineral shows have been displaying large volumes of inexpensive, massive calcite from Mexico. In both rough and fabricated forms, this calcite has a soft translucency and comes in pleasing shades of red, orange, yellow and white. Most distinctive, however, especially in rough pieces, is its smooth, lustrous, glassy surface, which still retains many of its original, irregular projections and concavities. Although this undulating surface may seem to be the product of mechanical polishing, it is actually created by a much faster, cheaper, and less labor-intensive method—brief immersion in acid.

Calcite, or calcium carbonate (CaCO₃), crystallizes in the trigonal system. It occurs in many crystal habits, of which the most familiar is well-developed rhombohedrons. With a specific gravity of 2.7-3.0, calcite is only slightly denser than quartz.

As a simple carbonate, the calcite molecule consists of a divalent calcium cation bound to a negatively charged (anionic) carbonate radical. The weak ionic bonding between the calcium ions and the carbonate radical explains many of calcite’s physical properties, including its relative softness of Mohs 3.0 and its tendency to cleave easily into rhombohedrons.

Weak ionic bonding also explains another of calcite’s diagnostic properties: its vigorous effervescence in acids. The term “effervescence” refers to a foaming or “boiling” effect caused by the release of millions of tiny gas bubbles. Effervescence was a traditional demonstration in high-school chemistry classes; instructors would mix an acid and a carbonate compound, usually sodium bicarbonate (baking soda), to produce the violent foaming that is the principle behind soda-acid fire extinguishers.

That same reaction occurs when acid contacts calcite. Using hydrochloric acid (HCl) as an example, calcite effervesces vigorously when the acid’s highly reactive chlorine ions (Cl^1-) break its weak ionic bonds and replace its carbonate radicals.

This reaction is stated by the formula CaCO₃ + 2HCl = CaCl₂ (calcium chloride) + H₂O (water) + CO₂ (carbon dioxide). The rapid release of carbon dioxide gas creates the bubbles of effervescence. Mineral-effervescence tests are usually performed with cold, dilute hydrochloric acid. Effervescence is apparent when just a single drop of this acid contacts a calcite surface.

While all carbonate minerals will eventually dissolve in dilute hydrochloric acid, only a few effervesce vigorously. The action of cold, dilute hydrochloric acid on dolomite (calcium magnesium carbonate) generates only a subtle effervescence. This is because closer atomic packing within dolomite’s orthorhombic crystal lattice strengthens the ionic bonds between the calcium and magnesium cations and the carbonate anions, making dolomite much less susceptible than calcite to the chemical action of acids.

Interestingly, acid-effervescence does not occur at all in aragonite, the orthorhombic polymorph of calcium carbonate. Although aragonite and calcite have identical chemistries, aragonite’s orthorhombic crystal structure has a much stronger ionic bonding that resists the action of acids.

In the massive calcite now mined in Mexico, the red and orange shades are caused by tiny, included particles of hematite (iron oxide) in various sizes. The smallest particles are believed to produce red, while larger particles create orange and yellow.

Much of this Mexican calcite is fashioned into cups, ashtrays, paperweights, figurines, and other decorative objects. Some, in pieces as large as 1 or 2 feet high, is kept in its rough shape to serve as home or office display pieces.

After it is roughly fabricated or sized, this material is briefly immersed in acid to dissolve a thin layer of the calcite, leaving a smooth, lustrous, glassy surface. By greatly reducing the scattering of incident light, this surface improves translucency and intensifies the internal colors. Acid immersion also eliminates or makes smooth any remaining saw or wheel marks on fabricated pieces.

Quick and inexpensive, acid immersion improves both the appearance and marketability of all that colorful Mexican calcite—thanks to that mineral’s diagnostic tendency to readily effervesce in acid.

The post The Acid-Effervescence of Calcite first appeared on Rock & Gem Magazine.

Mexican Crazy Lace agate is probably the best known and most widely used lapidary material since the 1950s. Whether it’s because of its various colors, sagenite sprays, translucent waves of colors with parallax, bull’s-eyes, or paisley-looking patterns with bright colors, Crazy Lace agate sure lives up to its name!

Mexican Crazy Lace agate comes from the state of Chihuahua, where the agate is embedded in limestone. Due to the mining techniques used and how the agate is encrusted with the limestone, it can be very hard to find solid pieces yielding whole patterns. What I have seen in the marketplace within the last five years is mostly fractured; however, since there’s always so much going on with the patterns and colors, it’s still fairly easy to find really good sweet spots in the slabs to make cabs from.

Crazy Lace is usually slabbed by cutting against the grain so that the waves of colors are showing. This is pretty easy to figure out how to do; if you wash off the piece, you can usually see which direction the patterns are running. This is not the only way to cut this material, though.

When you are ready to buy and are sorting through rough material, sometimes it’s best to know what you’re looking for. For instance, when a piece has a botryoidal side, there’s a good chance that if you slice that end section off and grind down a little way, you will obtain a very different pattern with “bull’s-eye” orbs. In my opinion, this is one of the most beautiful patterns you can achieve when cutting Crazy Lace.

Not all the material will have that layer, but it’s much like a treasure hunt, in which you keep cutting until you find your favorite piece. As with any material, when cutting, always wear a respirator mask to avoid breathing in any of the dust.

Cabbing Crazy Lace isn’t all that difficult. It’s a hard material, so it takes time and patience, but overall, it’s one of the nicest materials to cab. Grind the top edges of the waves slowly and not too aggressively, since doing so might cause it to separate between layers. I’ve had this happen many times. In fact, it usually will separate cleanly on a botryoidal layer within the stone. You can use that as a natural edge to your cab for a nice effect, or you can always epoxy the two layers back together and, after the glue cures, go back and resume grinding where you left off.

When you’re starting on the wheels, this material will cut and shape cleanly, but be sure that you have removed as many of the flat spots and deep scratches from the cab as possible by the time you reach the 220 grit. Then, once you move on to the 280 grit wheel, be sure to dry the cab off often and check your progress. You should not leave this stage with any scratches whatsoever.

From this point on, the cabbing process should be rather routine. The stone will even look almost completely done after the 1200 grit wheel, but I would suggest going up to as high as14000 to 50000 grit polishing wheel to get that remarkable mirror shine to your work. With Crazy Lace, there’s usually no need to go to any extra polishing agents, but depending on the material, sometimes you may need to polish on a leather buff with cerium oxide to gain that little added touch!

The post Mexican Crazy Lace Agate first appeared on Rock & Gem Magazine.