Tips For Cutting the Kal-Toh Design

1. Since we do not have the luxury of meetpoint faceting in this design, try to keep the visual proportions that Kim shows in the diagrams. Do not worry about getting the proportions perfect on rough grit laps, but work on getting the proportions of the facets closer each time you go to a new lap/grit.

2. Choose the optimal material to cut. Kim Lembke suggests that it be faceted in medium saturation garnet. I decided to facet the gemstone in golden citrine to give it a more dramatic effect by adding some extinction to the gemstone. Extinction is when the gemstone loses light and we see dark areas in the gemstone. To quote Tuvok, “Without the darkness, how would we recognize the light?”

Although this worked for my purposes, I would suggest following Kim’s suggestion and using medium saturated garnet or YAG, Yttrium Aluminum Garnet, a synthetic gem material used for optic and laser technology.

3. If you are a North American gem cutter, facet G1 after P2. Kim is from Australia and I have noticed that Australian gemstone designers tend to use a different cutting sequence on the pavilion. Their North American colleagues usually facet the girdle early in their gemstone cutting sequence. Regardless of when you facet the girdle, keep in mind that the crown is very high on this gemstone and you should leave enough room to cut the girdle and crown. The pavilion is the same depth as the girdle and crown both are high.

4. When faceting the pavilion, I do not cut P6 and P7 until I have polished all the other pavilion facets. This gives me the ability to be more precise with putting in the frosted facets of P6 and P7. I use a worn-out 1,200-grit lap to cut P6 and P7 to give me the frosted facets and dramatize the difference between these facets and the polished facets. I cut my frosted facets in my example in a similar proportion as shown in the diagram, however, I think a variation of thinner facets or polished facets for P6 and P7 would be a welcome variation.

5. When cutting the crown, the only meet points you have are on the table. Your table size will depend on the depth that you cut C2 and C3. The deeper you cut these facets (or the smaller C1 is) the larger the outcome of your table. Gauge the table size when cutting in C2 and C3 with your rough grit laps and refine your facet sizes as you progress with your finer grit laps. Keep an eye on the place and size of the table.

Give it a Try!

Kal-toh is a challenging gemstone to facet. In the game, “Kal-toh is to chess what chess is to tic-tac-toe” said Tuvok. I hope that you give this gemstone design a try and that my suggestions make the faceting experience a pleasant journey. Keep in mind that a no-meet-point design also gives you the ability to play with the proportions and the gemstone’s final outcome. As Captain James T. Kirk said, “Without freedom of choice, there is no creativity.”

This story about gem faceting the Kal Toh design appeared in Rock & Gem magazine. Click here to subscribe. Story by Mark Oros.

The post Gem Faceting: Kal-Toh Design first appeared on Rock & Gem Magazine.

About Barite

Barite has a Mohs hardness of 2.5 to 3.5 and crystallizes in the orthorhombic system. Barite is usually pale-colored and can be clear, white, yellow, blue, green or red. Its streak is white. Barite’s luster can be vitreous or pearl-like. Cleavage is prismatic.

Barite most often occurs in sedimentary rocks such as limestone and dolostone and in sediments that have weathered out of limestone. Barite can be found around hot springs and in nodules in clay. It can also occur in sandstone filling the voids between the sand grains and can form a rose shape, often stained with iron oxides, that’s popular with mineral collectors.

Barite Uses

Barite is used in paints and as an agent to add weight to rubber, cloth and paper. It is added to the paper used to produce playing cards to make them easier to deal. Barite is added to rubber to increase the life of the rubber product as the product becomes waterproof and its durability increases. Barite is also used to color fireworks green. 

Barite contains barium and is used in the field of medicine in the form of barium compounds to block x-rays in various diagnostic testing.

The major use (over 90%) for barite is its use in drilling muds. The barite mud carries the busted rock pieces produced by the drill and transports them to the surface and at the same time keeps the drill bit from overheating.

While barite is more common as a stone, it is used for metaphysical purposes to encourage the mind-body connection for self-healing and helps to dispel negative thinking.

Where to Find Barite

While most barite is mined in China and India, deposits occur in the Yukon, Nova Scotia and New Foundland in Canada as well as in Hermosillo, Pueblo, Monterrey and Durango in Mexico. In the United States, large barite deposits occur in Georgia, Missouri, Nevada and Tennessee.

This story about barite previously appeared in Rock & Gem magazine. Click here to subscribe. Story by Richard Gross.

The post Barite Mineral Field Guide first appeared on Rock & Gem Magazine.

In over a century of searching, riches are still found in the “Treasure State” of Montana. Initially earning this moniker for the gold, silver and copper finds, sapphires have solidly earned their place among the bounty of the State.

During the Montana gold rush in Southwestern Montana in the early 1860s, sapphires appeared as colorful distractions in the miners’ pans and sluice boxes. The colorful bits of sand and gravel were of little value. While gold was one of the main forces, followed by silver and copper, behind the creation of Montana as a territory and a state, if the miners knew what they had at the time, they wouldn’t have been as quick to toss them aside.

“They were after the gold,” says Cass Thompson, owner and operator of the Spokane Bar Sapphire Mine, roughly 30 miles northeast of Helena. Thompson’s family has mined this area for sapphires over the past 60 years.

How Montana Sapphires Were Created

Created as igneous rocks slowly cooled, sapphires are made of the mineral corundum, chemically known as aluminum oxide. With a Mohs rating of nine, sapphires are the hardest natural substances following the diamond.

Reaching the level of the sapphire-laden material can be a challenge. Bound in a conglomerate of feldspar and bentonite clay, sapphires tend to settle well below layers of topsoil, overburden, and evidence of volcanic activity in the gravel bars. In some parts of the Eldorado Bar along the upper Missouri River deposit, there are layers 100 feet below the surface making it more difficult to reach. But because of the sapphires’ high specific gravity of four (although much less than gold’s 19.3) these areas were often intermingled with placer deposits, which is why they were intertwined with the search for gold.

The Brilliance of Chemistry

“We have quite a variety of sapphires in Montana, but the mainstay is the Yogo,” said Glenn McCaffery, longtime gem enthusiast in Great Falls, Montana, and registered jeweler with the American Gem Society.

“The Yogo is untreated and of exceptional quality. There are very few flaws,” he explained. While mining for gold in 1895 along Yogo Creek in the Little Belt Mountains east of Great Falls, prospector Jake Hoover collected the brilliant blue stones instead of discarding them, and sent them to Tiffany & Co. in New York City for an assessment. It turns out these excellent quality gemstones earned Hoover and his partners $3750, over $3000 more than what they’d made finding gold.

While the beautiful “cornflower blue” of the Yogo is highly desirable, natural sapphire colors range from lighter blues, lavenders, pinks, greens, oranges and yellows. Combinations of titanium, iron, small amounts of chromium, and nickel result in this wide array of hues. The signature coloration of the Yogo is a result of titanium and iron, with the more iron involved, the deeper the blue. Rubies, which are also corundum and sometimes found in these areas, are brilliant red because of the presence of a higher concentration of chromium.

“In the Missouri River Deposit where we mine, we get the full spectrum of colors, but the most prominent is the blue/green,” said Thompson. He also notes they find a wide range of sizes.

More Valuable than Gold

“We’ve seen some really nice gem-quality sapphires up to a 26 facet grade,” said Thompson.

When searching for sapphires, sharp eyes are needed to pick out the tiny gems that are mere millimeters across, but larger stones closer to 10 carats are not uncommon. “The largest was found by my grandfather. He found a 50-carat stone. I’m still in the high 20s,” he said. To put it in perspective, Thompson said a 50-carat sapphire is roughly one and a half inches long and as big around as a man’s thumb.

The popularity and price of sapphires, especially since they are September’s birthstone, today would make early prospectors swoon. Thompson said some of the stones found on their place were valued between $1000 to $10,000 per carat. As an example, Thompson said a 24-carat sapphire cut to an 8 to 9-carat finish is easily worth $10,000 or more. “The value (of sapphires) is definitely more than gold,” he said.

Where Montana Sapphires are Found

Besides Yogo Gulch between Great Falls and Lewistown, which is no longer open to the public, there are many sapphire-rich areas throughout Central and Southwestern Montana, all of which coordinate with historic gold speculation. The gravel bars running along the upper Missouri River between Canyon Ferry Reservoir and into Hauser Lake, including the Eldorado and Spokane Bars, are some of the earliest finds and are still rich in sapphires. But after the construction of the dam in the early 1900s to create Hauser Lake, several of the gravel bars were submerged deep below the surface. It’s interesting to consider what sapphires are strewn along these now underwater former gold stakes when prospectors tossed the pretty stones aside.

More to the southwest, the Dry Cottonwood Creek (discovered in 1889) near Deer Lodge, as well as Rock Creek closer to Philipsburg, which was also found in the late 1800s, became popular sapphire mining areas. While the high-quality gems of Yogo Creek earned impressive amounts, many of the other sapphires initially found industrial uses, primarily in watchmaking, as well as being used in bombsights for torpedos and as the abrasive material on sanding wheels until the mid-1940s. After this time period, industrial operations shifted to synthetic sapphires to suit their needs. Since then, treasure hunters still gravitate toward several of these historic mining locations.

Want to Try your Hand at Finding your Own Montana Sapphires? Touch base with these knowledgeable operations for your treasure hunt. Spokane Bar Sapphire Mine Not far from the state capital of Helena, the Spokane Bar Sapphire Mine offers several digging options. Gem Mountain Sapphire Mine Located in Philipsburg, Gem Mountain offers material at a downtown shop or at the mine roughly 22 miles out of town. Montana Gems of Philipsburg Whether searching gravel on-site or having it shipped to your own, Montana Gems offers materials from Rock Creek and the Eldorado Bar areas. Sapphire Gallery Also in Philipsburg, the Sapphire Gallery offers materials from the Rock Creek deposit in the aptly named Sapphire Mountains.

Commercial Mining

Montana is the only state where sapphires are commercially mined, which includes providing opportunities for the public to try their hand picking through gravel to find treasure. Thompson said the basic premise of sapphire mining hasn’t changed very much over the past century. “Since we’ve been doing it, it’s pretty much the same. The equipment just gets bigger,” he says. Front-end loaders and excavators are the front line in removing the materials from the mining location before further processing.

For operations that sell gravel for individuals and families, it’s not a matter of simply dumping dirt and gravel into a bucket. Once extracted, the material goes through a trommel, a rotating drum that sorts out the larger rocks, followed by multiple screening and washing processes to refine the material to a manageable size. In the end, what’s left is a bucket of seemingly innocuous gravel and clay that is rich with sapphires, along with possibly topaz, hematite, garnets, fossils and even gold.

Digging Montana Sapphires

Is it legal to collect rocks, including Montana sapphires? Many commercial mines are open to the public throughout the state with the option of visiting the mining area and searching through the gravel outdoors in a beautiful setting. Some allow visitors to gather material to gain a better understanding of the process. Other places have storefront facilities where there is typically an option to purchase a bucket to sort through at the shop or buy materials to take home. Most mines can even ship bags of gravel.

The actual sorting process is fairly simple. Customers are given a shaker box, which is a screened, roughly three-inch tall container that allows the water to flow through the materials. It is filled about halfway with gravel, then washed in a large tub or trough.

Washing is somewhat of a zen moment. The rhythmic motion of gently working the shaker box in the water — submerge, tilt, flatten, turn, repeat — is surprisingly relaxing. With these movements in the water, the gravel rises, and because the sapphires are heavier, they sink below the layer. Washing also filters out the fine clay to make the gems more visible. After a few passes, it’s time to flip the box on the table so the sapphires are closer to the top.

It doesn’t take long to train your eye to see the pastel colors and different shapes, which are sometimes more rounded or potentially crystalline depending on the mine location. Tweezers are the tool of choice to pluck them from the gravel. Because there can be several different minerals among the sapphire material, if there is any question, save the stones and ask someone at the mine. With generations of experience, they’re happy to explain your find and answer questions.

As with many outdoor activities in Montana, operating seasons are dictated by the weather. Some of the indoor shops offer gravel washing throughout the year, but for those who want to hunt at the mine sites, it’s best to wait until the weather moderates. Thompson said that they’ll often continue mining into December, which can be a brutal month. If Mother Nature cooperates, they welcome visitors in March or April.

Treasure Hunting

Steeped in a long tradition of treasure hunting, Montana sapphires are a unique find in this extraordinarily beautiful landscape.

Picking through pay dirt, it’s easy to understand the allure of gold, and later these colorful gems, and why this quest never fails to spark the heart and imagination of those that appreciate the challenge.

This story about Montana sapphires previously appeared in Rock & Gem magazine. Click here to subscribe! Story by Amy Grisak.

The post Montana Sapphires 101 first appeared on Rock & Gem Magazine.

This was a unique find, and there has yet to be another like it since. Other popular petrified wood specimens include sycamore petrified wood and North Dakota’s teredo petrified wood. Hell’s Canyon Petrified Wood is known to be from the Cretaceous and Miocene era (25 to 145 million years ago). It displays beautiful wavy patterns, known as herringbone, which were the natural growth rings of the ancient Sequoia trees. It also contains dry rot holes that have since been filled with silica and micro drusy cavities.

How to Get Hell’s Canyon Petrified Wood

Hell’s Canyon Petrified Wood isn’t always the easiest of materials to find in the marketplace, but it still can be found in various places online and occasionally at shows. Most of what you find are slabs, and rarely do you see chunks of rough on offer. Not that buying slabs is a bad thing, it actually gives you a good view of exactly what you are buying. One thing to note when purchasing, the thicker the slabs, the better, as it tends to be quite brittle to cut and breaks easily. If you find thin slabs for sale, it’s not the end of the world; it just means you will need to back them before cabbing, which may be the best course of action in the first place, not risking breaking any of this rare and usually expensive material.

Prepping Slabs

Prepping your slabs for preforms is really important since you don’t want to lose any portion of your material. I would generally suggest bench testing slabs to see if there are hidden fractures and if the material will break at an early stage in the cabbing process, but with this material, you should just assume it can break at any spot. To avoid risking the entire slab, I usually cut one preform out closest to the edge of the slab, and start my usual cabbing process, and see how it responds. If it can cab without any hazards, you’re good to go with the remaining portion of the slab. If it was too brittle and portions broke off, then you know to back the entire slab first before trimming out any further preforms.

Backing your slabs is generally easy, as various epoxies can be used. Many people like to back their cabs with black basanite, or you can choose something that has the same general color combinations as what you are cabbing, possibly another type of petrified wood. Spread out a generous amount of epoxy around the edges of your slab, and fill the center as much as possible to avoid any air pockets. I like to use spring clamps to add pressure all around the glued areas, compressing and expanding the glue to the entire area, and allowing it to ooze out the edges. It’s better to use too much epoxy than not enough, and just tip the slab up at an angle to dry, allowing the excess glue to drip onto something that can be discarded.

Cabbing Hell’s Canyon Petrified Wood

Cabbing this material is fairly easy. It just needs to be worked with a gentle touch. Starting with an 80 grit steel wheel may be too aggressive for this type of material, as it’s fairly soft, to begin with, and as stated, brittle. So I would suggest starting on a 220 grit steel wheel to shape and dome your cab. Be cautious not to get the dry rot holes too close to the edge, or you might possibly break open the holes, leaving an uneven edge. Once you have your preform cab shaped and domed, move on to the 280 grit soft resin wheel; from this point, you should be able to apply a generous amount of pressure and smooth your cab out, and check thoroughly for any remaining scratches. Once the scratches are completely gone, move to your 600 grit and continue as a usual jasper-type cab.

Once you’ve reached the 14k grit polishing wheel, this is probably as far as you need to go, as it takes a beautiful polish and the patterns will just pop. Trying to use polishing compounds might fill in the tiny dry rot vugs and create heat fractures from the friction of the polishing pads.

This What to Cut column about Hell’s Canyon petrified wood previously appeared in Rock & Gem magazine. Click here to subscribe! Story by Russ Kaniuth.

The post Hell’s Canyon Petrified Wood first appeared on Rock & Gem Magazine.