At an early age, John became curious about his uncle’s line of work, but his queries were often met with vague responses. As an adult, he devoted much time and effort to researching his uncle’s history.

The following is John’s perspective of that history, a few stories of the everyday life of the scientists, plus a quick rundown of naturally occurring radiation, including radioactive rocks, present in our lives today.

Philip Grant Koontz

Uncle Grant met his wife, Florence Eyre while both were undergraduate students at Hastings College in Nebraska where he earned a bachelor’s degree in 1927. He earned a master’s degree from the University of Nebraska before earning his doctorate in physics from Yale.

After graduating, Grant served as an associate professor of physics at Colorado State University. Here is where the history becomes clouded in secrecy. Sometime during Grant’s tenure at Colorado State, he met and assisted Arthur H. Compton on Mt. Evans in his studies of cosmic rays.

In 1942, Grant was asked by Compton to join Enrico Fermi and the other scientists in Chicago at the “Metallurgical Lab,” for the creation of the Chicago Pile (CP-1). Shortly after the Chicago scientists achieved a sustained nuclear reaction, Grant and his family were spirited off to Los Alamos, New Mexico. Now the secrecy was stepped up.

Science, Secrecy & Real People

While both in Chicago and Los Alamos, the scientists worked feverishly on what is now called The Manhattan Project. But as history and several photos handed down through the Eyre family prove, those scientists were real people with families and interests outside of their laboratories. While still in Chicago, Uncle Grant and Aunt Florence hosted a picnic at their home. Family photos show that Enrico Fermi, his wife and young daughter, and a few unidentified scientists attended.

Once at Los Alamos, Grant took photos of several of the scientists collecting selenite in an area outside of the compound. Rockhounding must run in the family! But everyday life was hard for both the scientists and their families. All mail to friends and relatives was sent via a post office box in New York City and was carefully censored to remove any reference as to where they were, what they were doing or even anything about the weather. Grant could never tell his wife where he was going when he disappeared for days while testing bombs at Trinity Site or the Nevada Test Site.

Once some of the secrecy was lifted, Grant liked to tell a story about how he and a few of his fellow scientists discovered a hole in the Los Alamos compound fence. For fun, instead of simply telling the authorities about the security breach, a few scientists took their family dogs for a walk outside the compound. They signed out at the gate, proceeded to the hole in the fence; crawled under the fence and proceeded to sign out at the gate a second and third time before the guard caught on and they finally told him about the hole.

An Atomic Timeline

It’s time to tell the real history of these men. An easy way to do that is by using a timeline of their achievements.

The culmination of all of this work was the bombing of Hiroshima and Nagasaki in August 1945, which effectively ended WWII. Our world was forever changed and the discoveries of these scientists are still present in our day-to-day lives.

Rockhounding

Radioactivity didn’t just appear in our lives with these discoveries, it was always naturally occurring in our rocks and minerals. The most common radioactive minerals found in nature are uranite, thorite, pitchblende and carnotite.

One of the byproducts of atomic bomb testing is “trinitite.” Scientists gave this name to the desert sand which fused into glass caused by the heat of the first atomic bomb test on July 16, 1945, at the Trinity Test Site, outside of Alamogordo, New Mexico. Uncle Grant sent several samples to John’s dad, a chemist who cast them into paperweights made of Lucite plastic.

Radioactive Food, Medicine & Household Items

Probably the most common food containing a radioactive isotope (K-40) of potassium is bananas. Not to worry, you would need to eat 70,000 bananas to get the equivalent radiation of a chest CT scan. Small amounts are also found in potatoes, kidney beans, sunflower seeds or any food containing potassium.

On the other hand, Brazil nuts contain small amounts of radium isotopes approximately 1,000 times higher than those found in other foods. Some salt substitutes contain small amounts of radioactive potassium (K-40).

Many generic brands of antidiarrhea medication contain kaolin clay that has elevated levels of uranium and thorium.

Still, no worries, as you would have to consume over 1,000 pounds a year to exceed the current EPA maximum exposure level. The name brand of this drug has discontinued use of kaolin clay.

Ionization-type smoke detectors contain small quantities of americium-241. Never try to disassemble one of these units.

Kitty litter contains bentonite clay which is measurably radioactive. The contents include uranium, thorium and potassium-40. Also, potassium chloride water softener salt contains measurable amounts of potassium-40. A standard 50-lb. bag would never make it past the highly sensitive radiation monitors used at nuclear power plants.

Radioactive Collectibles

Uranium Glass

Early civilizations used minerals to add color to their glass and pottery. Uranium, or Vaseline glass as it is sometimes called, was not known to be radioactive until 1896. However, some earlier glassware contained radioactive colorants for over 2,000 years. It is usually yellow to green and is fluorescent under UV light. It contains two to 25% uranium oxide and is slightly radioactive.

Uranium glass is collectible and was made into various items from everyday glassware to bowls, knick-knacks and souvenir items. The bowl this author’s grandmother used to make gelatin in every week as well as her special occasion stemware is still a part of our family’s collection.

Orange Fiesta Tableware

Uranium oxide has been added to ceramic glazes for many years to color pieces orange-red. The Homer Laughlin Company used it to produce their bright orange Fiesta tableware from 1936 to 1943. Its use ended in 1943 when the company’s supply of uranium oxide was commandeered by the U.S. government for use in atomic weapon production. To this day, all of these original pieces are fairly radioactive and should NOT be used for food purposes, but only as radioactive collectibles.

Lantern Mantles, Metal Alloys & Welding Rods

Non-nuclear uses of thorium compounds are limited. Thorium oxide is the coating used on gas lantern mantles in older camping lanterns. It’s what causes the lanterns to incandesce at high temperatures. Several types of nickel alloys have thorium oxide added to them to increase their strength.

Thorium oxide is also used as an additive to some tungsten-based welding rods. TIG welding rods are available with a 2% thorium content to help in arc stabilization and are slightly radioactive.

3M Model C-15 Tape Dispensers

Next time you wrap a present, take note of your tape dispenser. If it is old and exceptionally heavy, it may be one of the 3M company dispensers made in the 1970s. These models were filled with monazite sand for ballast. Monazite is a radioactive mineral containing thorium.

More Items

There are more radioactive collectibles than can be listed in detail, but here are just a few more:

• Firestone Brand Polonium Spark Plugs from 1946 to 1953—contain polonium

• Radium watch and clock hands—contain radium

• Glow-in-the-dark gun sights—contain tritium

• Military ballistic projectile penetrators— contain depleted uranium

• Cloisonne jewelry with orange or yellow glaze—contains uranium oxide

• Radio Brand Golf Balls 1910 to 1930— contain radium

• Gilbert Atomic Energy Lab Kit, sold in 1951-1952 as a child’s educational tool, was deemed to be dangerous and taken off the market. They are still available on the internet for upwards of $2,000 to $4,000—contain samples of autunite, carnotite, torbernite & uranite

Plan a Visit

Hands-on learning opportunities about the Manhattan Project and the Atomic Age are available with planned visits to various sites across the U.S. The National Park Service sponsors sites at Los Alamos, Hanford and Oak Ridge. You may want to visit the Bradbury Science Museum in Los Alamos. Special tours of Trinity Site and the Nevada Test Site are available on a limited basis and may require registration and possible security clearance.

Radioactivity has been and always will be present in our world. To the rockhound, if handled and stored properly, radioactive minerals and collectibles can provide an interesting addition to mineral collections.

This story about radioactivity previously appeared in Rock & Gem magazine. Click here to subscribe. Story by Sue Eyre.

The post Radioactivity, Rocks & The Men Who Handled Them first appeared on Rock & Gem Magazine.

A few prospectors did indeed make their fortunes. Still, most received their reward by participating in an adventure that thrilled the nation and introduced words and terms like “radioactivity,” “Geiger counter,” and “radiometric prospecting” into the general vocabulary.

Although finding a million-dollar uranium deposit today is unlikely, understanding radioactivity and knowing how to detect it can greatly enhance the mineral-collecting experience. Radioactivity is one of the fascinating physical properties of minerals. It is ionizing energy in the form of particles and rays produced by the spontaneous disintegration or “decay” of unstable atomic nuclei.

Understanding & Identifying Radioactivity

While this definition might seem a bit intimidating, getting a practical handle on radioactivity is not that difficult. Admittedly, the word is loaded with negative connotations linked to nuclear weapons, fallout, toxic waste disposal, reactor meltdowns, and the hazards of radon gas. Nevertheless, radioactivity is very much a part of the natural world, especially the world of mineralogy.

Minerals are described as radioactive when they emit energy in the forms of alpha, beta, or gamma radiation. “Radiation” is the catchall term for energy in the form of waves or particles. Gamma rays make up the extreme high-frequency, shortwave end of the electromagnetic spectrum, broadband of radiation energy that includes radio waves, microwaves, infrared, visible light, ultraviolet, and X-rays.

Alpha and beta particles are not forms of electromagnetic energy. Alpha radiation refers to positively charged, high-energy, low-mass particles that consist of two neutrons and two protons (the nuclei of helium atoms). Beta particles can be negative or positive; negatively charged beta particles are high-speed electrons, while positively charged beta particles are positrons (the “antimatter” counterparts of electrons).

Exploring Ionization

Alpha particles, beta particles, and gamma rays (along with X-rays) are classified as “ionizing” radiation, meaning that they have sufficient energy to ionize atoms in the materials they strike. Atoms become ionized when they lose electrons and assume a net positive charge. Because it disrupts normal biochemical functions on the molecular and atomic levels, ionizing radiation can be harmful to living tissue. Ionizing radiation is produced by nuclear fusion, nuclear fission, and atomic decay, the latter being the natural disintegration of the nuclei of unstable, heavy elements or isotopes (elements with different numbers of neutrons).

Ionizing radiation can be cosmic, man-made, or geophysical in origin. The sun, a giant nuclear fusion furnace that emits intense gamma radiation, provides most of our cosmic radiation. Fortunately, very little reaches the Earth’s surface because of its distance from the sun and atmospheric absorption. During the past 80 years, the Earth’s cumulative environmental radiation load has increased significantly due to uranium mining and processing, nuclear weapons manufacture and resting, nuclear power and X-ray generation, accidental radiation releases, production of radioactive isotopes for medical and industrial uses, and radioactive waste disposal.

Geophysical Radiation

Mineral collectors, rockhounds, and prospectors are most interested in geophysical radiation, which is emitted by natural radioactive elements that are present in minerals as essential or accessory components. Most geophysical radiation is produced by uranium and thorium, which occur in trace amounts in many igneous rocks, especially granite. The effects of geophysical radiation go far beyond surface radioactivity. An estimated 80 percent of the Earth’s internal heat is produced by the atomic disintegration of uranium, thorium, and the elements and isotopes in their atomic-decay chains.

Of the 92 naturally occurring elements, 11 are radioactive. Of these, only uranium and thorium are relatively abundant. Uranium was identified as an element in 1789; it was isolated in 1841 as a very dense, silvery-white metal that oxidizes rapidly in air. Ranking 51st in crustal abundance, uranium is about as common as tin.

Thorium, discovered in 1828, is similar in appearance to uranium but is half as dense and much more common. Until the discovery of radioactivity, uranium and thorium were little more than laboratory curiosities. Small quantities of uranium oxides were used to color glass yellow, while thorium compounds that incandesce (emit visible light) when heated were employed in gas-lantern mantles.

Driven by Discoveries

The discovery of radioactivity followed investigations into the mysterious, penetrating “invisible energy” that was produced by passing an electrical current through vacuum-discharge tubes. In 1895, the German physicist Wilhelm Conrad Röntgen (1845-1923) named this energy “X-rays” to signify its unknown nature. Radioactivity was accidentally discovered in 1896 when French physicist Antoine-Henri Becquerel (1852-1908) studied the effects of X-rays and sunlight on potassium uranyl sulfate, a compound that fluoresced in direct sunlight. Becquerel placed this compound atop photographic plates wrapped in lightproof black paper, then exposed it to sunlight.

He noted that the photographic plates became exposed and attributed this to some type of penetrating energy related to fluorescence.

When cloudy weather delayed his experiments, Becquerel stored both the uranium compound and the unexposed, wrapped photographic plates together inside a dark desk drawer. Later, out of curiosity, he developed the plates and found they had already been exposed. This exposure meant that the uranium compound—without any induced fluorescence—continuously emitted invisible, penetrating rays. Becquerel then demonstrated uranium itself, not its compounds, was continuously emitting these rays, which became known as “uranium rays” or “Becquerel rays.”

Marie Curie & Ernest Rutherford

Among the first to investigate these rays was Marie Curie (1867-1934), the Polish-born French chemist and physicist who coined the term “radioactivity.” In 1898, after extracting uranium and thorium from uraninite (uranium oxide), Curie was surprised to find that the uraninite was still highly radioactive. Concluding that it must contain additional sources of radioactivity, she extracted two previously undiscovered radioactive elements—polonium and radium. The radium was particularly interesting because of its extraordinarily intense radioactivity.

In 1902, British physicist Ernest Rutherford (1871-1937) proposed that radioactivity consists of what we now know as alpha and beta particles, and gamma rays. He found that alpha and beta particles lose their energy relatively quickly as they pass through materials, while gamma rays have a far greater penetrating power. Until the discovery of radioactivity, most scientists believed that the smallest particle of matter was the atom, which was indivisible and unchangeable. But Rutherford challenged the idea of atomic indivisibility by proposing that alpha and beta particles were subatomic components of disintegrating atoms. This concept opened the door to modern particle physics and an entirely new understanding of the nature of matter and energy.

Early 20th Century Proves Progress

The early 1900s saw many exciting discoveries about radioactivity. While working with thorium, Rutherford had detected radioactivity throughout his laboratory—even after the thorium had been removed. He deduced that this radioactivity came not from the thorium itself, but from a gaseous product of thorium’s atomic disintegration. This realization led to the discovery of another radioactive element—radon.

Rutherford then postulated that radioactive elements spontaneously and continuously disintegrate to release radiation and produce a decay chain of other radioactive elements and isotopes. He also learned that radon’s intense radioactivity decreased by half every few days. His term “half-life” is now used to describe the speed at which unstable atoms undergo atomic disintegration.

Rutherford observed that an inverse relationship existed between half-life and the intensity of radioactivity. Uranium, with its low level of radioactivity, has a very long half-life of more than four billion years. But extremely radioactive elements such as radium and radon have very short half-lives. Unfortunately, the effects of ionizing radiation on living tissue were not understood. While exposure to radioactivity seemed to halt the growth of certain cancers, it also caused burns and open lesions on the skin of many researchers. Nevertheless, hopes that radiation would cure cancer and boost general well-being created a huge demand for radium, some for research purposes, but mostly to be used in patent medicines and bizarre therapeutic devices.

Mining Uranium Ore

The aspect of research triggered the first significant mining of uranium ore—not for uranium, but the ore’s tiny traces of radium. The important radium sources were uraninite from the historic Joachimsthal mines in what is now the Czech Republic and the carnotite (hydrous potassium uranium vanadate) ores of western Colorado. By 1912, radium was the most valuable commodity in existence and cost $100,000 per gram—nearly $2.5 million in today’s currency.

Initially, radioactivity could only be detected with photographic plates and fluorescent screens; it could be crudely measured with gold-leaf electroscopes and complex, piezoelectric-quartz devices. Then in 1908, German physicist Hans Geiger (1882-1945) constructed a sealed, thin metal cylinder with a wire extending down its center. After filling the tube with inert gas, he applied an electrical voltage almost strong enough to pass between the electrodes, in this case, the wire and the tube walls. When exposed to radioactivity, the gas ionized to become conductive, completing the circuit and producing an audible click. These electrical discharges instantly returned the gas ions to their normal energy level, making it possible to continuously and immediately detect additional radioactivity and measure its intensity by “counting.”

Although the first “Geiger counters” were ponderous instruments sensitive only to alpha particles, they were vital to the early studies of radioactivity. In 1928, Geiger and his colleague Walther Müller designed a new tube. Now known as the Geiger-Müller counter, it is sensitive to all forms of radioactivity and is still used today.

Greater Understanding and More Utilization

The uses, perception, and importance of radioactive minerals changed radically during World War II when uranium became the source of its fissionable U-235 isotope needed for the first atomic bombs. Following the war, the United States government subsidized the “Great Uranium Rush,” in which improved, lightweight, shoe-box-sized Geiger-Müller counters were the key tools for the thousands of radiometric prospectors who searched for “hot rocks,” mainly uraninite and carnotite. The radioactivity emitted by uranium and thorium has several effects on minerals, one of which is color alteration.

Long-term exposure to low-level radioactivity can disrupt normal electron positions in the crystal lattices of certain minerals. This activity creates electron traps, called “color centers,” that alter the mineral’s color-absorption-reflection properties. The colors of smoky quartz, blue and purple fluorite and halite, brown topaz, and yellow and brown calcite are often caused by exposure to geophysical radiation.

Metamictization

Another interesting effect is metamictization, which occurs in some minerals that contain accessory amounts of uranium or thorium. In metamictization, geophysical radiation displaces electrons to slowly degrade the host mineral’s crystal structure. Metamictization is usually apparent in crystals as rounded, indistinct edges, curving faces, and decreased hardness and density. Metamictization can sometimes completely degrade crystals into amorphous masses.

Metamictization is common in the rare-earth minerals gadolinite (rare-earth iron beryllium oxysilicate) and monazite (rare-earth phosphate). Because of their similar atomic radii, uranium and thorium often substitute for rare-earth elements to make their minerals radioactive. California’s huge Mountain Pass rare-earth-mineral deposit was actually discovered by a uranium prospector equipped with a Geiger-Müller counter.

Zirconium Silicate

Zircon, or zirconium silicate, another mineral subject to metamictization, has an additional connection to radioactivity and is employed in radiometric dating, which uses known rates of atomic decay to determine the age of ancient rocks. Because of similar atomic radii, uranium substitutes readily for zirconium in zircon. The uranium-238 isotope has an extremely long half-life of 4,468 billion years. The inert, extremely durable zircon “protects” the traces of uranium—an ideal combination for the radiometric dating of ancient rocks.

When igneous rocks solidify from magma, their contained traces of uranium have not yet begun to decay. By measuring the extent of atomic decay, geophysicists can determine when the sample crystallized. The oldest known rocks are found in Australia. Based on partially decayed traces of uranium-238 contained in tiny zircon crystals, these rocks have been dated at 4,374 billion years—only a few hundred million years after the formation of the Earth itself.

Detecting Radioactivity

Today, mineral collectors have access to a wide range of radioactivity-sensing instruments, including dosimeters that measure cumulative radiation exposure, miniaturized Geiger-Müller counters, and scintillators that quantitatively measure geophysical radioactivity, and radiation monitors that measure relative overall radioactivity. Prices for basic instruments begin at about $40, while top-of-the-line, quantitative instruments can cost thousands of dollars.

Choosing the Radiation Monitor For You

For general mineral-collecting and amateur radiometric-prospecting uses, radiation monitors, which cost from $200 to $700, will suffice. I’m familiar with the Radalert™ radiation monitor manufactured by International Medcom of Sebastopol, California. It weighs 10 ounces and contains a miniaturized Geiger-Müller tube. Alpha and beta particles, gamma rays, and X-rays ionize the tube’s gas atoms, causing the tube to discharge with tiny electrical pulses. Integrated circuits convert these pulses to liquid-crystal displays, flash light-emitting diodes, and generate audible clicks.

This instrument detects total ionizing radiation (a mix of geophysical,

cosmic, and man-made radiation) and provides relative, rather than absolute or quantitative, radioactivity measurements. It is ready for use after quickly determining the local background radiation “load,” which varies with geology, solar-flare activity, and elevation.

At sea level, the normal background radiation might be roughly 13 counts per minute. But at a mountain elevation of 7,000 feet where there is less atmospheric shielding of cosmic radiation, the background level might be 30 counts per minute. Radiation monitors can even detect temporarily elevated levels of cosmic radiation due to increased sunspot activity.

Background Radiation

Background radiation also varies with local geology. Radiation levels near granite outcrops are usually higher than in other areas because of traces of uranium within the granite. Radiation monitors can serve as a safety tool to detect elevated levels of radioactivity from potentially hazardous accumulations of radon gas in living spaces. They can also detect the very low levels of alpha radiation emitted by household smoke detectors.

Smoky quartz sometimes has detectable traces of radioactivity, while gadolinite, monazite, and other rare-earth minerals have levels that are easily detectable. When used with such uranium-bearing minerals as canary-yellow carnotite and tyuyamunite, yellowish-green-to-green autunite, and green torbernite, radiation monitors “sound off” with hundreds or thousands of counts per minute.

Among the interesting radioactive collectibles is yellow “uranium glass,” which was popular in the early 1900s and still emits detectable levels of radioactivity. Another is greenish trinitite, quartz sand that was fused together by the world’s first atomic detonation on July 16, 1945, at New Mexico’s Trinity Site. Trinitite specimens, which are still sold today, have low but easily detectable levels of radioactivity.

Proper Handling

Collecting radioactive minerals is not dangerous when precautions are followed. One rule is to collect small specimens. Cumulative radiation and the amount of radon gas emitted by radioactive specimens are directly proportional to specimen size. There is no need to collect cabinet-sized specimens of carnotite, even though they are easily found on mine dumps.

Handle radioactive specimens minimally and always wash hands thoroughly afterward. Never eat, drink, sleep or, smoke around radioactive specimens, and always keep them out of the reach of children. Also, radioactive specimens should be clearly labeled as such and stored in well-ventilated spaces away from living areas.

Radiation monitors can add a new dimension to many field-collecting trips. And they are an absolute necessity when exploring the thousands of uranium mine dumps scattered across the Four Corners regions of Colorado, Utah, and New Mexico. Radiation monitors make the difference between finding nice specimens of brightly colored, oxidized uranium minerals and finding nothing at all.

Collectors should never enter an abandoned mine, but abandoned uranium mines are particularly hazardous. These unventilated mines have accumulated extremely high concentrations of intensely radioactive radon gas.

Anyone interested in the history of radioactivity will enjoy visiting these two New Mexico museums: The Bradbury Science Museum at Los Alamos National Laboratory in Los Alamos, and the National Nuclear Museum of Science and History in Albuquerque. Both contain a wealth of exhibits and information on radioactivity—one of the fascinating physical properties of minerals.

This story about radioactive rocks previously appeared in Rock & Gem magazine. Click here to subscribe. Story & photos by Steve Voynick unless otherwise indicated. 

The post Radioactive Rocks: A Rockhound’s Guide first appeared on Rock & Gem Magazine.

• Spectacular Silver Boulder Treasures: An Exhilarating New Arizona Find. By Helen Serras-Herman

• Crystal Twinning: A Special Mineral Form. By Bob Jones

• Hot Rocks: A Rockhound’s Guide to Radioactivity. By Steve Voynick

• Passion for Paleontology: Getting to Know Father-Daughter Duo Paleo Joe and Paleo Jen. By Antoinette Rahn

• Summer In the San Juan Mountains (Part II): Gold Quartz, The Hope Diamond, And a Cast of Characters. By Bob Jones

• Mineral County Wanderings: Chance Encounter Creates Opportunity to Mine for Variscite. By Bruce McKay

In addition, you’ll find the following regular R&G columns: Bench Tips with Bob Rush, Rock Science with Steve Voynick, What to Cut with Russ Kaniuth, On the Rocks with Bob Jones, Just Off the Wheels with Erin Dana Balzrette, Rock & Gem Kids with Jim Brace-Thompson, The Road Report with Helen Serras-Herman, Virtual Adventures, Picks & Pans, Show Dates, and the always popular Parting Shot.

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The post Issue Highlights July 2020 first appeared on Rock & Gem Magazine.