Minerals are all around us and even within us. Consider iron in your blood or calcium in your bones. While humans have always sought food products, we’ve always used rocks. Our ancestors used cobbles as hammers to crack nuts. We later learned to use obsidian, chert, and flint to knap knives and spear points and to spark fire. We’ve moved on from the Stone Age to the Copper, Bronze, and Iron Ages. Minerals and related earth resources continue to enable contemporary life and the built environment in which we live. They include metals, nonmetallic minerals, and fossil fuels. How little we appreciate this fact of life!

Take the Common Pencil…

Something as simple as a pencil requires more minerals than you might imagine. While a pencil casing is painted wood with a hollow core, the rod within the core is a combination of graphite (carbon) and kaolinite (clay). The more kaolinite, the harder the rod. This is why we have #2, #3, and other pencil grades that leave either a wide dark streak or a slender light streak. While the pencil eraser is a natural or synthetic rubber, it may contain pumice to provide grit. Holding that eraser to the pencil is a tube constructed of aluminum (from bauxite) or brass (from copper plus zinc, or sphalerite). Four to six minerals in a common pencil. Who knew?!

To appreciate the number of minerals used in everyday life, deconstruct other objects. A salt shaker often has an aluminum top (derived from bauxite) and a glass body (from sand, or silicon dioxide) and is filled with salt (halite) crystals. Although it’s on its way out, an old-fashioned incandescent light bulb has a glass exterior (made from silica, soda ash, lime, coal, and salt), a brass or aluminum screw-in base, a tungsten filament, copper and nickel lead-in wires, molybdenum tie and support wires, and an aluminum heat deflector.

Explore Minerals Contributing to the Build Environment

Here are some fun and easy exercises to introduce kids (and yourself ) to the many minerals contributing to our built environment.

Match the Product to the Mineral

An Interactive Display & Quiz

Perfect for a school project…Construct an interactive display showing everyday items at the back and the minerals that went into them at the front. For instance, a soda can at the back and a specimen of bauxite (aluminum ore) at the front, or matches at the back and sulfur at the front. Provide a quiz for kids to fill out to match a mineral to a product.

Spin the Wheel!

For more immediate interactive fun, have a board laid out with squares numbered and stocked with different economic minerals. Kids spin the wheel. They then need to name a product made from a mineral on the number where the wheel lands. If they guess correctly, they keep the mineral. Stick with fairly easy and obvious choices (e.g., a copper nugget matched to plumbing pipes) and have a poster or chart nearby that kids can consult.

The Home Scavenger Hunt

In a school classroom, rock club meeting room, or a home, gather kids around a flipchart, chalkboard, or whiteboard. Encourage them to look around and list everyday things and the rocks and minerals that went into them. If using an old-fashioned chalkboard, you can start with the chalk and the slate of the chalkboard. You might go throughout an entire house, or focus on a particular room.

Here are just a few examples: a brass lamp, windows made of silica, many things made of plastic derived from petrochemicals, fireplace bricks derived from clay (kaolinite), a tin cup, a gold wedding ring, walls made of plasterboard comprised of gypsum, steel nails, and screws in the furniture and paint on the walls containing diatomite as filler.

A Hardware Store Scavenger Hunt

Take a field trip for a scavenger hunt at a hardware store. To get started, here are a few things to seek:

• aluminum and tin siding or roofing (from bauxite or cassiterite)

• bricks and ceramic products (from fired clay, or kaolinite)

• diatomaceous earth for swimming pool filters

• drill bits and saw blades used for cutting tile, concrete, etc. (from diamond)

• electrical wiring, pipes, and plumbing fixtures (from copper)

• glass (from silica sand)

• plaster and drywall (from gypsum)

• rough and crushed rocks and stones for ornamental use (scoria, limestone, marble, etc.)

• sand for mixing with concrete, for sandboxes, etc.

• slabs of various sorts (granite, marble, etc.) for kitchen countertops

• steel and iron nails (made from iron ores like hematite)

Make Your Own Collection

Entire collections can be made of the raw materials of our built environment. Many common minerals are inexpensive and readily available from show dealers. As a start, consider pennies and a copper nugget; nails and hematite; fluorinated toothpaste and a fluorite crystal; laundry detergent and borate minerals; table salt and halite crystals; matches and sulfur.

Learn More!

Several websites provide handy tables linking minerals to everyday objects. Here’s a sampling:

• Minerals Education Coalition

• Women in Mining

• United States Geological Survey (USGS)

• American Geosciences Institute (AGI)

• Gemological Institute of America (GIA)

• National Mining Association

• AFMS Future Rockhounds of America Badge Manual

How Minerals Shape History

As we humans progressed from the Stone Age to the Electronic Age, we’ve seen all sorts of ages in between dominated by a search for earth resources. Consider gold rushes, wars of conquest for mineral-rich colonies, and “titans of industry” (Carnegie, Rockefeller, Peabody, Getty). Our current age is obsessed in a quest for minerals for electric batteries built with lithium, and cobalt. These resources are eagerly being sought to move us from a carbon-emitting petroleum-dependent economy to one based on clean energy.

However, keep in mind that clean electric energy still requires dirty mining. If you think we can get to a so-called no-cost energy future, think again! There will always be a need for mining and minerals, along with a cost to pay. How we ultimately balance such costs is what matters. Think we can live without minerals and all that goes into extracting them? Think again. Think wisely.

What Made It?

Pencils or smartphones are just the beginning. There are thousands of minerals and even more applications of those minerals. Here’s a tiny selected sampling…

This story about the minerals used in everyday life previously appeared in Rock & Gem magazine. Click here to subscribe. Story by Jim Brace-Thompson.

The post Minerals Used in Everyday Life first appeared on Rock & Gem Magazine.

Minerals and Metals of the Bible: Timeline

Biblical archaeologists study ancient cultural sites and artifacts to gain insight into the Bible’s Old and New Testaments. Combining archaeology with scriptural interpretation provides a clearer understanding of life as it was and the events that occurred during the biblical period, which extends from 3300 B.C. to the first century A.D.

Archaeologists divide biblical history into three general periods based on the dominant material used in tools and weapons: Stone Age, Bronze Age and Iron Age.

Holy Land Topography

The Jordan Rift Valley dominates the Holy Land’s topography. This rift system began forming 35 million years ago with a westward separation of the African tectonic plate from the Asian plate and fractured the crust into long, parallel faults. The crust between the faults subsided, sometimes thousands of feet, to create a long, linear sequence of narrow rift valleys. The East African Rift System, including the Jordan Rift Valley, is still widening today.

The Jordan Rift Valley extends from Lebanon south for 300 miles to the Gulf of Aqaba. Within it is the Jordan River, the Sea of Galilee, the Dead Sea and the desolate Wadi Araba, all features of biblical significance.

Main Metals of the Bible

The Bible mentions six metals: gold, silver, lead, tin, copper, and iron. Although not mined in the Holy Land, gold and silver played major roles in biblical history. The Bible mentions gold more than 400 times, and silver nearly 300 times.

Metals of the Bible – Gold

During the biblical period, just as today, gold served as a store of value, a symbol of wealth and prominence, and a jewelry metal. It was obtained in trade mainly from sources in Egypt, the Arabian Peninsula, India, and the Sinai Peninsula.

Metals of the Bible – Silver

Silver was scarce in the Holy Land until the Greeks developed the great Laurion silver-lead mines in the fourth century B.C. Silver coins such as Greek drachmas and staters, Roman denarii (the Bible’s “tribute pennies”) and Tyrian shekels, were the standard mediums of exchange throughout the greater biblical region.

Metals of the Bible – Lead

There’s also yielded large amounts of lead which, in the Holy Land, served as rebar in the construction of stone buildings. Holes drilled through adjoining stone blocks were filled with molten lead which then solidified to secure the blocks in place.

Metals of the Bible – Copper

Copper had a great impact on the Holy Land, and most came from the Timna Valley in Wadi Araba near Eilat, modern Israel’s southernmost city on the Gulf of Aqaba. Timna Valley copper occurs as both sulfide and oxide minerals that are emplaced in granite, dolostone and sandstone. Pre-dynastic Egyptian cultures were mining these rich deposits as early as 4000 B.C. Miners initially collected nodules of copper minerals from the surface; later, they followed outcrops underground to carve out large systems of passageways and galleries.

Biblical scholars have long debated how Solomon, the fabulously rich king of Israel from 970 to 930 B.C., amassed his fortune. Many believed that Solomon owned gold mines. But in the 1930s, an American archaeologist suggested that the legendary “King Solomon’s Mines” were the Timna Valley copper mines, an idea initially discredited because the ruins, at that time, could not be dated to Solomon’s reign.

But in 2013, Israeli archaeologists accurately carbon-dated organic remains from the Timna Valley ruins to 930 B.C. — the end of the great king’s reign. Most biblical scholars now agree that copper from the Timna Valley, the world’s earliest example of systematic copper mining, was indeed the source of Solomon’s wealth. Today, the valley, a remote, arid region of spectacular pillars, arches, and canyons, is the site of Timna Valley Park and an adjacent nature preserve. Exhibits at the park museum represent 6,000 years of copper mining.

Metals of the Bible – Iron

Thanks to supplies of Timna Valley copper and Kestel tin, the Bronze Age dawned in the Holy Land about 3300 B.C. Bronze, a copper-tin alloy superior to copper in hardness, durability, and workability, was the primary metal for tools and weapons for the next two millennia. (Many Bible translations erroneously refer to bronze as “brass,” which is a modern copper-zinc alloy.)

About 1500 B.C., the Hittite Empire in Anatolia began smelting iron from bog iron ores. Described in the Old Testament as adversaries of the Israelites, the Hittites produced tempered, carbon-steel alloys that were harder and more durable than bronze, and could be fashioned into sharper-edged weapons. Iron weapons, armor and chariots, the latter a landmark military advancement, soon made the Hittites a feared regional power.

The Hittites zealously guarded their iron-smelting methods. When their empire collapsed around 1250 B.C., Hittite ironworkers scattered throughout the greater Mediterranean region to bring the Iron Age to various regional cultures. By 1200 B.C., iron, obtained from hematite and magnetite deposits in Syria, Anatolia and Wadi Araba, was in widespread use throughout the Holy Land.

Metals of the Bible – Tin

The world’s first great source of tin was Kestel in the Taurus Mountains of Anatolia (now south-central Turkey), where the mining of placer and vein deposits of cassiterite or tin dioxide began about 3400 B.C. Caravans traded this tin throughout the Middle East and beyond. The Kestel ruins contain miles of narrow tunnels and dozens of small smelters that reduced cassiterite to metallic tin.

Minerals and Metals of the Bible – The “Eilat Stone”

The national stone of Israel, “Eilat stone,” also known as “King Solomon’s stone,” consists of intergrowths of blue-green masses of azurite, malachite, chrysocolla and turquoise. Specimens and polished cabochons of Eilat stone have been popular souvenirs of Israel since the nation was founded in 1948. But the specimen supply ended when the last commercial copper mine closed in the 1980s. Since then, much Eilat stone sold in Israel and abroad is similarly colored material from the copper mines of Africa and Arizona.

Main Minerals of the Bible

Minerals of the Bible – Alabaster

Another carving material was alabaster, a dense, fine-grained, compact form of gypsum, or hydrous calcium sulfate, which often occurs in limestone formations. Translucent and often displaying subtle patterns of honey-yellow colors, alabaster is soft and easily carved. Polishing brings out a warm glow similar to that of marble. Alabaster was fashioned into goblets, sculptures, vases, and funerary urns. (Some “alabaster” artifacts from the biblical period consist of the travertine form of calcium carbonate, which has a similar appearance.)

Minerals of the Bible – Soapstone

Stone carvers also worked with soapstone or steatite. Soapstone, a metamorphic rock consisting primarily of talc, or hydrous magnesium silicate, is the softest mineral at Mohs 1.0. It has a “soapy” feel and colors ranging from off-white to grays, blues, browns, and greens. The softest and most desirable carving grades contain about 80 percent talc. Soapstone artifacts from the Holy Land include bottle stoppers, cylinder seals, beads, and figurines. Most of this soapstone came from metamorphic formations in the mountains of present-day Syria and Turkey.

Minerals of the Bible – Brimstone

The Bible mentions brimstone 14 times, always as an idiomatic expression for the wrath of God, as in “fire and brimstone.” The English word “brimstone” is derived from the Old English brynstan, literally meaning “burning stone,” referring to its ability to burn in air. Brimstone is elemental sulfur that frequently occurs in volcanic environments, hence the Old Testament’s association with fire, hell, and God’s retribution. In biblical times, sulfur had many uses in medicine, and as a fumigant and disinfectant.

Sulfur occurs at several sites in the Jordan Rift Valley which, like all rifts, has numerous remnant volcanic fumaroles and active thermal springs, some with condensate and evaporite sulfur deposits.

Minerals of the Bible – Limestone

Two common, often-overlooked mineral resources of great importance in biblical history are limestone and clay. Much Holy Land bedrock is limestone, a marine sedimentary rock consisting of at least 50 percent calcium carbonate. Limestone forms when calcareous skeletal and shell remains of marine life accumulate on sea bottoms, mix with other sediments and lithify into massive formations.

Jerusalem rests atop thick formations of fossiliferous, fine-grained, oolitic limestone with buff, pink, green and brown colors. Since the city was permanently settled around 3000 B.C., this late-Cretaceous Period limestone, now known as “Jerusalem stone,” has been used in much of Jerusalem’s construction.

Jerusalem stone was also the raw material for making lime or calcium oxide. Finely ground stone was calcined (heated) to drive off the carbon dioxide from the contained calcium carbonate, leaving behind white lime.

Multicolored limestone mosaics were a popular art form in the Holy Land during the Roman occupation. Stoneworkers cut colored limestone into thin, half-inch-square, inlay pieces to create elaborate mosaics for interior décor.

Minerals of the Bible – Salt

It’s not surprising that the Bible refers to salt (halite, sodium chloride) more than 30 times. During the biblical period, salt was a widely traded commodity that was used as a food seasoning and preservative, a disinfectant, a ceremonial offering, and even a monetary-like unit of exchange. The Holy Land’s main source of salt was the Dead Sea, which is fed by the Jordan River and has no outlets. Continuous, rapid evaporation in the desert climate maintains the salinity of the Dead Sea at 34 percent, nine times higher than that of seawater. Thick shoreline salt encrustations were the first regional sources of salt.

By 1000 B.C., the systematic mining of rock salt had begun at Jebel Usdum (Mount Sodom) on the Dead Sea’s northwest coast. Jebel Usdum is a five-mile-long, 720-foot-high ridge consisting almost entirely of layers of rock salt that formed 10 million years ago when seawater repeatedly flooded the deepening Jordan Rift Valley and then evaporated. Mining peaked in the second century B.C. when camel caravans regularly transported tons of rock salt to distant markets.

At the southern end of the Jebel Usdum ridge, a 100-foot-tall spire of rock salt is known as “Lot’s wife,” alluding to the Old Testament account of the destruction of the cities of Sodom and Gomorrah in which Lot’s wife, while fleeing the city of Sodom, ignored God’s warning not to look back and was turned into a pillar of salt.

Minerals of the Bible – Pitch

Another Dead Sea resource was pitch, or natural asphalt, which is referred to in the Old Testament when God instructs Noah to build an ark and “cover it inside and outside with pitch.” This pitch originated as bituminous (hydrocarbon-rich) limestone. The heat and pressure of deep burial altered the bitumen into partially developed petroleum that mixed with silt and clay, lost its volatile components and formed thick layers of natural, black asphalt. Parts of the Dead Sea floor consist of layers of pitch that sometimes floated to the surface where they were collected, cut into pieces, and shipped to markets.

During the biblical period, most of this so-called “Dead Sea stone” was sold to Mediterranean shipyards as hull-caulking material. Some was traded to Egypt where it was used to waterproof papyrus boats and to Mesopotamia to serve as building mortar. Because high bitumen pitch burned like coal, it was also used as a fuel. Solid, black pieces of pitch, similar in density, color, and carving properties to jet, were fashioned into ornaments.

Minerals of the Bible – Natron

The Bible also mentions “nitre” or natron (sodium carbonate decahydrate), which was used as a soap, antiseptic, disinfectant, food preservative and medicinal compound. Some natron was obtained from the Dead Sea, but most came from northeast Egypt’s huge Wadi el Nutrun (Natron Valley) evaporite deposit. Utilizing its hygroscopicity, the Egyptians employed natron extensively in mummification.

By 1000 B.C., natron’s most important use was in making glass, or “crystal” in the biblical terminology. Glass, which was then very valuable and even served as a gemstone, was made from silica sand, a lime stabilizer and a natron flux to lower the silica’s melting point.

By the first century B.C., new glassblowing techniques could create thin-walled glass vessels in virtually any shape. During the Roman occupation of the Holy Land, glassmakers began producing high-refraction glass by adding lead oxide to the glass mix to increase density and thus refractive index and brilliance.

Minerals of the Bible – Clay

Clay was another common mineral resource of great importance in biblical history. Wet clay has a plastic consistency and is easily moldable. It is mixed with various tempering or stabilizing materials, then fired in ovens where it dries, loses its plasticity, and hardens into permanent, molded ceramics.

By the early biblical time, making ceramics had become a well-developed skill and art that produced pottery, storage vessels, funerary urns, beads, ceremonial objects and writing tablets. Writers used styli to impress characters into soft, wet clay which was then fired into durable tablets.

Many priceless biblical artifacts have survived within ceramic jars. One of the best-known examples came to light in 1947, when a Bedouin herdsman discovered caves in the limestone cliffs along the northwestern shore of the Dead Sea. These caves contained ceramic jars holding one of the 20th century’s greatest archaeological discoveries—the Dead Sea Scrolls. The scrolls are written mostly on parchment, with a few inscribed on papyrus and one on a copper sheet. Without the protection of clay jars, archaeologists believe none of the scrolls would have survived.

Biblical Gemstones

Along with minerals and metals, the Bible also mentions gemstones, notably those of the sacred breastplate of the high priest of the Israelites. Familiarly known as “Aaron’s breastplate” or the “breastplate of judgment,” this golden breastplate was set with 12 different gemstones representing the 12 tribes of Israel and dates roughly to the 14th century B.C.

The Old Testament describes the breastplate and its gemstones in detail. But over many centuries as the original ancient Hebrew text was translated into Greek, Aramaic, Latin and, finally, English, the gemstone identities have become uncertain.

New interpretations of Old Testament scripture combined with modern archaeological and mineralogical data, along with historical information about the availability and sources of specific gem materials during the early biblical period, is providing new ideas about the identity of the breastplate gemstones.

This story about minerals and metals of the Bible previously appeared in Rock & Gem magazine. Click here to subscribe! Story by Steve Voynick.

The post Minerals & Metals of the Bible first appeared on Rock & Gem Magazine.

Our Iron-Rich History

Iron minerals played a major role in our history. After the Bronze Age came the Iron Age. Iron also plays an important role in our health. We are red-blooded thanks to the atoms of iron in every red blood cell. It grabs oxygen, carries it where needed, and releases it. Without it, we would be anemic and die.

Some iron minerals like magnetite, or lodestone, are attracted to a magnet. Others are not. Iron minerals like siderite and hematite are not affected by a magnet because the iron in them is combined in a mineral compound different from magnetite.

Understanding Magnets and Magnetic Force

We know that for a magnet to work things must line up internally. The “things” are electrons, which have to spin in the same direction creating a north-south influence. This is why nails, or needles, become magnetized from electricity, which flows in one direction.

Stroking the needle in one direction with a magnet will magnetize it. But once formed, are magnets permanent? Over time a magnet’s strength may slowly weaken. Hitting, or dropping it, will disrupt the electron spin and disrupt the alignment of electrons and magnetism.

The same thing happens with magnetite. Its electrons all spin in the same direction. Aligning in the same direction dictates the strength of the magnetism. The electrons of an element, like iron, also influence the chemistry of minerals.

Forming a Mineral

All elements are composed of protons and electrons. Forming a mineral requires an element acting as a metal, called a cation, which gives up its electrons to form a mineral. Iron does this and is positively charged as a result.

To form a mineral compound, a non-metal, like oxygen, takes in electrons and becomes negatively charged. This negatively charged non-metal oxygen joins the positively charged iron to form a mineral compound.

Iron and oxygen can join in a variety of ways to form compounds, so we get different iron minerals, magnetic magnetite and non-magnetic hematite, siderite ad infinitum and even rust.

What are Iron Minerals? – Magnetite

Most mineral collectors are familiar with minerals centered on iron-like magnetite, a natural magnet. Magnetite tends to be black in color, lustrous and is found in many locations. Its crystals are cubic in the isometric system, but cubes are not common.
It more often develops in octahedrons and less often in 12-sided dodecahedrons.

Magnetite usually occurs as small octahedrons, or tiny grains, in a variety of rock types. When crystallized, it is often found as simple octahedrons to an inch on an edge.

Fine examples of octahedral magnetite have regularly been dug by rockhounds on Twin Peaks, Millard County, Utah. The octahedrons are usually under an inch in sharp clusters.

One major use of magnetite in early history was in the Age of Navigation to indicate north and south. A type of magnetite, called lodestone, was used in navigation and is named “lode,” which means “journey.”

What are Iron Minerals? – Lodestone

During the second century BCE, early people were naturally curious about lodestone because of its magnetic property. In China, they found that if they floated a lodestone needle on water it would indicate direction. A liquid “compass” wasn’t used on a ship, but if the needle was suspended in air, it would indicate direction.

A compass works because the earth itself is surrounded by a life-saving magnetic field. What’s very interesting, and maybe scary, is we know the earth’s magnetic field reverses. We just don’t know why or know the consequences.

Be that as it may, it’s a good thing the earth has a magnetic field because it protects us from most of the lethal radiation constantly discharging from the sun. Some of that radiation, like ultra-violet rays, does penetrate. But the earth’s magnetic field makes life as we know it possible.

Earth’s Formation: The Core

Since we depend on the earth’s magnetic field, we need to know what produces this life shield. To understand, we have to look at the earth’s core. We can’t peer that far into the earth, so we must use other means. Earthquakes are one way to “look” into the earth.

An earthquake causes the entire earth to vibrate. The rock structures of the earth can slow, speed up, or deflect those vibrations which tell us something about the rock layers within the earth.

From this, we are convinced the earth’s innermost core is a solid nickel-iron suspended in an outer semi-liquid nickel-iron-rock core. As the earth rotates, the inner core rotates slower creating that all-important magnetic field.

If we are right about the earth’s core where did the iron come from? The general theory is that the earth was formed by accretion, the repeated crashing together of individual rocky masses, comets, and meteors as gravity pulled them in. That material was leftover from ancient exploding stars.

Note that iron, atomic number 26, is the heaviest element that a star like ours can create by atomic fusion. Gravity pulled all this space debris together to form the earth 4.6 billion years ago and we are still growing.

Earth’s Formation: The Crust

So why are the heavier elements like gold not deep in the earth? We find them in the crust. Luckily, crustal movement caused by great internal heat causes super hydrothermal solutions to bring the heavier elements up into the crust and we mine them!

During the earth’s early millennium, the crust was rich in meteorite iron while the earth’s early atmosphere was methane, ammonia, and carbon dioxide. Then an organic life form called stromatolites developed photosynthesis, which takes in carbon dioxide and produces oxygen changing the atmosphere. Oxygen, combined with the available iron in the crust, form massive amounts of iron compounds like rust, hematite, siderite, magnetite and other iron minerals.

We now find these huge iron oxide deposits and mine them in Australia, Alabama, Minnesota and elsewhere. The huge Mesabi iron range, among others, are what made America a huge steel producer.

We have to be grateful to magnets and the earth with its magnetic field. Its slowly rotating nickel-iron core has made life possible on earth and protected it so we can enjoy the benefits of our red blood cells as we collect iron minerals magnetite, hematite and siderite all the while dealing with annoying hydrous iron oxide: Rust!

This story about iron, the Earth’s Protector, appeared in the August 2021 issue of Rock & Gem magazine. Click here to subscribe! Story by Bob Jones.

The post What are Iron Minerals? first appeared on Rock & Gem Magazine.

Many specimens may carry the name axinite. But in actuality, axinite describes a group of similar and closely related but slightly different minerals.

According to information at www.minerals.net, the general composition of axinite is that of a basic aluminum boro-silicate of calcium, iron, magnesium, and manganese. The minerals that compromise this group are axinite-(Fe), axinite-(Mg), Axinite-(Mn), and Tinzenite. The Mineral of the Week is a specimen of axinite on offer at mineral-auctions.com. 

The name itself is inspired by the presentation of the sharp-edged crystals, similar to that of an ax, or in Greek terms, axine, which is what inspired the name of this mineral group in 1787. Sometimes, the crystal also appears in groups of rosettes of sharp crystals instead of a singular columnar blade or blades.

In terms of coloration, axinite specimens are known to be dichroic, meaning revealing different colors when viewed at different angles. The most common colors are smoky brown, purple-brown, greenish-brown, gray, and even black. Among the less common but still reported axinite colors are green, purple, orange, and yellow.

This week’s featured specimen of axinite [axinite-Fe] was discovered in the Canta Province, Lima Department, Peru. According to information in the lot description at mineral-auctions.com, it presents as a root-beer brown formation of wedge-shaped, sharp crystals. An interesting point of the crystal is what appears to be arrowhead growth patterns. The specimen is rather substantial in size, measuring 10.2 x 9.1 x 4.9cm and 338 grams.

The specimen is offered for auction by Joe and Michelle Weisberg via mineral-auctions.com. Learn more and bid: http://egmediamags.com/url-tracking/tracking?id=OEhnQkErMEJ5MWRjNWdwMkhwNEp4dz09

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Chemical erosion involves weathering done by interactions between chemicals in water (usually a dilute form of acid, as in acid rain) and in rocks or sediments, especially carbonate sediments like limestone that dissolve in acid. Such erosion is especially common in areas with abundant carbonate rocks and warm, wet conditions that facilitate chemical reactions, or oxidation.

The most vivid examples of chemical erosion are caves and sinkholes created in areas with a lot of underground limestone that ends up dissolving from acidic groundwater. Oftentimes, such caves are created by a combination of chemical and physical erosion as underground stream channels form, dissolving limestone sediments via both chemical and physical actions.

Air and Rock Interaction Activity

Chemical erosion sometimes also is caused by an interaction between air and rock, as when oxygen interacts with rocks containing iron, thus causing the iron to oxidize, or to become rust. This is often seen with iron minerals like hematite and magnetite. It also is seen with marcasite (a form of iron pyrite) that will disintegrate in the presence of oxygen-rich moisture, with the iron content turning to rust (iron oxide) and the sulfur content turning to sulfuric acid.

In addition, plants such as lichens that grow on rocks can produce weak acids that chemically weather and erode rocks. Such chemical erosion, whether from acids in rain or organic acids from plants, creates caves and cave formations and degrades man-made objects such as monuments and gravestones. Should you wish for future generations to bow before you, I suggest that you choose non-acidic granite—not marble—to mark your gravesite!

The post Geology 101: Weathering and Chemical Erosion first appeared on Rock & Gem Magazine.

Rock & Gem continues to celebrate the chemical elements since the United Nations declared 2019 the International Year of the Periodic Table of Chemical Elements. The discovery of many of the elements during the last five centuries is fascinating and as full of detective suspense as any murder mystery.

In the On The Rocks column of the March issue, we described how Hennig Brand, in the mid-1560s, accidentally discovered phosphorus while searching for the elixir of life. This was the first element extracted from a compound. By that time the alchemists studying matter were changing and the modern science of chemistry was emerging. Scientific principles were being developed and the search for elements became a formal not accidental scientific quest.

By the 1500s we already knew of a number of naturally occurring elements. Gold, copper, mercury and several others were found in their natural state though they were not recognized as true elements that could not be changed through ordinary chemical means.

Changes Due to Chemistry

While gold, copper, and silver were found in their natural form on earth, two of the earth’s very common metals, aluminum (Al#13) and zinc (Zn#30) are not. Aluminum is the basis for the common mineral family, and the feldspars make it the most common metal in the earth’s crust. Yet it remained hidden in pure form until the mid-1800s. When finally produced, aluminum was so rare it was more valuable than gold. It was struck into coins like gold and silver and displayed with the French crown jewels. My how things have changed thanks to chemistry!

Zinc is the fourth most common metal in the earth’s crust preceded only by aluminum, iron, and copper. We get most of our zinc from the zinc sulfide sphalerite and several more beautiful secondary species like smithsonite, zinc carbonate, and hemimorphite, and zinc silicate hydroxide hydrate.

Today we have many uses for zinc. The uses include coating steel and iron to prevent oxidation or rust, and alloying with copper to form brass. We use zinc in the electronics industry, and every breath you take depends on zinc in a compound, because it is important in removing unwanted carbon dioxide from your lungs!

Zinc minerals have been around since the earliest days of mining. The great silver mines of Laurium (Lavrium), Greece supplied silver so the Greeks could build ships to defeat Xerxes over 2,000 years ago. Incredibly, smithsonite from this ancient deposit is still seen for sale today.

Impact of Zinc Extraction

However, zinc does not occur naturally on earth, only in compounds. But according to various historical documents, apparently, zinc had been extracted in its ‘pure’ form in 1347, in the country of India. It’s believed, the Chinese probably smelted it first, most likely from smithsonite, which is one of the easiest zinc minerals to smelt. The process of obtaining zinc through smelting was even documented by the Chinese. Suffice to say the Chinese were eons ahead of the Europeans in many ways at that time. They invented paper, the seismograph, the compass, gunpowder, and a few other useful things long before Europe came out of the Dark Ages!

It was not until the early 1700s that European scientists began smelting calamine (hemimorphite) to obtain zinc, which was initially a waste by-product of smelting. Andreas Marggraf is credited with the scientific extraction of zinc element. He combined calamine with charcoal in a sealed vessel, heated it intensely, and obtained pure zinc that could be scientifically tested to determine the true chemical properties. Only then was zinc deemed to be an element and could take its place on the periodic table.

Of all the elements discovered through scientific research and experiments, the oddest one has to be germanium (#32). You may recall from reading my column in the March issue that germanium was unknown at the time Dimitri Mendeleev developed his first Periodic Table of Chemical Elements in the mid-1800s. As he worked, Dimitri recognized that elements could be grouped by their similar chemical properties into certain families. As he listed the known elements by their properties, he left spaces for the elements he thought ought to be there based on properties of known elements. He even gave names to three missing elements, ekaboron, ekaaluminum and ekasilicon, which were discovered at a later date. Ekaalminum was eventually found and named gallium (Ca#31). Ekaboron was eventually discovered to be scandium (Sc#21). Ekasilicon turned out to be germanium (Ge#32). The first two were discovered as solids and were easily observed and collected. Germanium is normally a liquid at room temperatures, which Mendeleev predicted, and therein lies the mystery of its discovery.

It all began when scientists were examining the complex silver ores from the Himmelsfurst mine, near Freiberg, Saxony, which had been worked since its discovery a thousand years earlier. These ores are rich in silver and a variety of other elements. It was not until the 1880s that a new mineral appeared in the Himmelsfurst mine ores and was named argyrodite. At the time this new mineral’s chemistry was unknown and became the subject of a study by German Professor H.S. Richter. He was able to identify silver and sulfur in the new mineral, but more work was needed.

Furthering Silver Ore Exploration

Clemens A. Winkler took over the process to obtain a complete analysis of the new

mineral argyrodite. Winkler searched the new mineral for antimony, tin and other known elements. Once he had extracted every known element from the ore what remained had to be the missing component, the new element. He evaporated all the remaining solution, but when he checked his apparatus there wasn’t anything there! Whatever had been there had disappeared! How could that be? Undaunted he spent four more months working on the material, retorting, evaporating, chemically treating, filtering on and on without success.

Then one morning as he walked into his laboratory he happened to glance up at the ceiling. The ceiling was covered with a white powder that should not have been there. It was the missing material. It had turned to a liquid during his experiments just as Dimitri had predicted. It had evaporated unseen and condensed on the ceiling. The white powder contained the new element, which was easily extracted in pure form. Winkler had finally found germanium!

You might ask if Winkler’s endless search was worth it? Of what use was germanium? It seemed to have none and was considered just another element. But in World War II we found a use for it in making semiconductor diodes, and transistors, among other devices. Germanium suddenly became very useful and still is as a component of modern electronics.

Do you realize that if you lived in the early 1700s and suddenly died it could have been from lack of dephlogisticated air? A prevailing theory at the time was that objects could only burn and animals only breathed because of phlogiston in the air. Luckily, there was another school of thought that argued there was some unknown element in air, not phlogiston, which was needed. Phlogiston is a word from the Greek meaning “burning up.” The thinking was that once the phlogiston was depleted in the air, burning and breathing stopped.

Understanding the Oxygen Theory

The theory scientists had, and was proved to be right was the oxygen theory. Oxygen was necessary for burning to happen. The problem was that no one had isolated oxygen or phlogiston and neither theory could be proven. Scientists in several countries, including England and Sweden, worked diligently to prove the existence of the life-giving gas and debunk the phlogiston theory. We now know the gas is oxygen. Where would we be without oxygen to form many minerals?

Englishman Joseph Priestley is credited with producing the first sample of oxygen, although it’s reported he thought he had produced phlogiston. Just before Priestley discovered his life-giving gas, Swedish druggist Carl Scheele had done the same thing. Scheele had produced oxygen but did not publish his findings. Priestley published his findings and in turn received the credit. Scheele showed his gas could keep a candle burning. Priestley, on the other hand, not only showed his gas would keep a candle burning but would also keep a mouse alive. Oddly, Priestley chose to call his gas dephlogisticated air. It was not until the French scientist Antoine Lavoisier, the Father of Modern Chemistry actually identified the gas and named it oxygen.

Lavoisier was brilliant. He proved sulfur was an element and predicted the properties of the then unknown element that is so important in the electronics industry today, silicon (Si#14). Lavoisier was also sure that Priestley’s dephlogisticated air was necessary for the formation of all acids. He was wrong but decided to give Priestley’s gas a name based on Greek ‘oxys,’ which means sharp or acid, and mistakenly named the life-giving gas “acid former.”

Unfortunately, Lavoisier, a true genius, was a nobleman during the French Revolution. His government job was as a tax collector. When the Revolution got going all tax collectors were judged to be “stealing from the citizens” so all were condemned to the guillotine, including Lavoisier.

Highlighting Helium

There is one element, helium, which was first found in space, not on earth. It was recognized in the gaseous corona of the sun. Now we find it in quantity on earth as one of the many components in natural gas found in petroleum deposits. When someone hands you a floating balloon you are actually holding a container of helium. If you breathe it in your voice sounds funny because the density of helium is less than air. We use it in lighter-than-air ships and in other ways, like food preservation to keep oxygen away from the food, especially fruit.

Norman Lockyer first suggested helium as being in the sun’s atmosphere but many laughed him at. Later, he was vindicated when he studied a radioactive mineral and found helium as one of the mineral’s components. By the 1920s, we were finding it in quantity as one of the gases in natural gas. We now know it is the lightest of the Noble gas elements and is not flammable.

Helium was just one of the gases in the sun’s atmosphere. Scientists began to identify elements in the sun, of which there are dozens, by using a prism or other device to spread sunlight in the same manner as a rainbow. In studying the light spectrum in sunlight German scientist, Joseph von Fraunhofer among others recognized dark lines in the sun’s color spectrum. These were later realized to be absorption lines caused by gases of different elements in the sun’s atmosphere. These gases were absorbing certain light waves emitted by different elements in the sun’s atmosphere. We could duplicate the lines here on earth proving the sun was producing those same elements. This led to another avenue of research into the origin of elements in space and here on earth.

More interesting stories of the search for the chemical elements will be described in a future On the Rocks column.

The post Suspenseful Discovery of Elements first appeared on Rock & Gem Magazine.

Earthquake Prevention: Not So Easy as Once Thought

The February 2 issue of Science News Magazine reports how 50 years ago, the Federal Council for Science and Technology recommended a 10-year program to study ways to defuse potential earthquakes. One of their proposals: inject fluids to ease strain along fault zones and produce numerous small earthquakes as opposed to waiting around for “the big one”.

Flash forward 50 years! We now know that, far from ameliorating earthquake risk, underground fluid injection actually amplifies it, as evidenced by increased numbers of relatively large earthquakes in such areas as Oklahoma, which has seen fracking and fluid injection to increase oil and natural gas production.

With the benefit of hindsight, we now know that such a practice falls into the category of “be careful what you wish for”!

Zimbabwe Gold Miners Perish

For the lucky gambler, mining may offer a big pay-out, but it also always has been a risky enterprise. After all, it involves high explosives, excavation of steeply walled pits, deep underground tunnels, heavy machinery and super-sized vehicles, encounters with noxious gases and dust, and more.

During heavy rains in the Kadoma mining district of Zimbabwe, a dam wall collapsed on February 12, immediately inundating the tunnels of numerous small-scale gold mines and instantly trapping miners as deep as 130 feet below ground. As of February 16, 9 miners had been pulled out muddied but alive after waiting for rescuers in water that rose to their necks. But bodies were recovered of 20 others who were not so lucky. All 20 were found in just one of the many tunnels in the area. While estimates vary wildly, some say as many as 38 to 60 miners, in all, may have been underground at the time, and all those not yet rescued are now feared dead.

Many of the Kadoma miners are so-called subsistence or artisanal miners; in other words, folks who scratch out a living using rudimentary methods that are not formally regulated and thus often lack even basic safeguards. Furthermore, the Rio Zimbabwe company, which owns one of the flooded mines (the Cricket Mine), noted that they had ceased operations some time ago and had sealed shafts, which some of the missing miners apparently had illegally breached, according to a company spokesperson.

Illegal and unauthorized mining is common in Zimbabwe (over half its annual gold production comes from such small-scale miners), particularly given a deep economic crisis throughout the country and extreme rates of unemployment. That economic crisis is hampering relief efforts, with the government appealing for aid from “individuals, development partners and the corporate world”. Meanwhile, rescue teams continue frantic efforts to pump water from flooded shafts as family members of the missing continue to hold out hope.

A Slab Off the “Old Woman” Goes to College

What weighs 3 tons, is the second-largest of its kind ever found in the United States, and got mired in a long custody battle? Welcome to the “Old Woman”! The Old Woman is a 3-ton iron meteorite named for the Old Woman Mountains near Twentynine Palms, California, where this guest from space was discovered by prospectors in late 1975.

A custody battle promptly ensured. Who owned the Old Woman? The folks who found her? The U.S. government and its national museum, the Smithsonian Institution in Washington, DC? The State of California? Courts decreed in favor of the U.S. government, and from 1978 to 1980, she was displayed at the Smithsonian. She now resides on long-term loan at the Desert Discovery Center in Barstow, California (http://desertdc.com/old-woman-meteorite/).

Meanwhile, Professor John Wasson recently welcomed the long-term loan of a beautifully etched slab of this famous old gal for display in the Meteorite Gallery within the Geology Building on the campus of UCLA. The Gallery is open daily to the public, with special days set aside for docent-led tours and for presentations and guest speakers. Check it out at https://meteorites.ucla.edu.

The post Earth Science In the News: ‘Old Woman’ Meteorite At UCLA first appeared on Rock & Gem Magazine.

Manganese is an element that we rarely, if ever, see in its metallic state, but that nevertheless plays a big part of our everyday lives. Manganese is present in everything from alloyed steels and aluminum beverage cans to clear glass, colored brick, and dry-cell batteries.

Elemental manganese and iron both have steel-gray colors and similar atomic weights. Manganese is much harder, however, and so brittle that it cannot be machined. It ranks 12th among the elements in crustal abundance. Because of its great affinity for oxygen, it does not occur on Earth in elemental form, but is sometimes found as a native metal in meteors.

Neolithic Art With Manganese

The most abundant manganese-bearing mineral is pyrolusite, or manganese dioxide (MnO2). Pyrolusite was used as a pigment in the black paints that Neolithic artists used to create Europe’s 17,000-year-old cave paintings. The exceptional hardness of the iron weapons of the ancient Greeks was due to the accidental incorporation of manganese into molten iron. The Romans later utilized pyrolusite in glass making, adding small quantities to decolorize glass and larger quantities to impart dark colors.

The name “pyrolusite” stems from the Greek words pyr (fire) and lousis (washing), and alludes to the mineral’s ability to remove color from molten glass.

By the mid-1700s, scientists began to suspect that pyrolusite contained a previously undiscovered element. In 1774, Swedish chemists Carl Scheele and Johann Gottlieb Gahn heated powdered pyrolusite with carbon to chemically reduce the compound and isolate a new metal that they named “manganese” (the Italian word for pyrolusite).

Growing Demand

In the 1880s, metallurgists alloyed manganese with iron to create the first high-quality, modern steels. The earlier carbon steels, while hard, were too brittle for many applications; manganese steels were much harder and far less brittle.

In the early 1900s, the growing industrial demand for manganese was satisfied by mining shallow deposits of pyrolusite. Pyrolusite, which crystallizes in the tetragonal system, usually occurs in massive forms or as radial aggregates of acicular crystals. It has a substantial Mohs hardness of 6.0-6.5, a specific gravity of 4.2, a steel-gray color, and a semimetallic luster that is sometimes accompanied by a bluish iridescence.

Because manganese has five common oxidation states (+2, +3, +4, +6, and +7), it forms numerous oxides, basic oxides, and hydrous oxides that include such minerals as manganite, manganosite, hausmannite, romanèchite and hollandite. These often occur together and can be very difficult to distinguish from pyrolusite. Such mixes of manganese oxides are known as “psilomelane”, or by the mining term “wad”.

Today, pyrolusite and braunite (manganese silicate) are the primary ores of manganese, about 18 million metric tons of which are mined each year. South Africa leads the world in manganese production, thanks to the huge Kalihari manganese fields, which are familiar to mineral collectors as a source of fine specimens of rhodochrosite (manganese carbonate).

Sources of Manganese

Other important manganese sources are China, Australia, Gabon and Brazil.

Although the United States is the leading manganese consumer, it has not mined manganese ores in 50 years and is completely dependent upon foreign supplies.

Ninety percent of all manganese is alloyed with steel. Because the atomic radii of iron and manganese are almost identical, manganese atoms can substitute for those of iron without distorting iron’s crystal lattice. While creating hard, non-brittle steel alloys, manganese also enhances iron’s ability to take on the desirable qualities of other alloying metals such as molybdenum, vanadium and chromium. Manganese also imparts corrosion resistance to the aluminum alloys used in beverage cans.

Pyrolusite serves as the electrolytic paste in dry-cell batteries and a decolorizing agent in glass manufacturing. Architectural brick contains various manganese compounds that, when fired, convert to manganese dioxide to produce a range of colors.

Many field mineral collectors have had first-hand experience with pyrolusite, but might not know it. In manganese-rich mineral deposits, it’s that omnipresent black powder that quickly stains skin and clothing.

The post Rock Science: Pyrolusite and Manganese first appeared on Rock & Gem Magazine.