Copper – A Metal Used Through The Ages
Copper was one of the first metals ever extracted and used by humans, and it has made vital contributions to sustaining and improving society since the dawn of civilization. Copper was first used in coins and ornaments starting about 8000 B.C., and at about 5500 B.C., copper tools helped civilization emerge from the Stone Age. The discovery that copper alloyed with tin produces bronze marked the beginning of the Bronze Age at about 3000 B.C.
Copper is easily stretched, molded, and shaped; is resistant to corrosion; and conducts heat and electricity efficiently. As a result, copper was important to early humans and continues to be a material of choice for a variety of domestic, industrial, and high-technology applications today.
How Do We Use Copper Today?
Presently, copper is used in building construction, power generation and transmission, electronic product manufacturing, and the production of industrial machinery and transportation vehicles. Copper wiring and plumbing are integral to the appliances, heating and cooling systems, and telecommunications links used every day in homes and businesses. Copper is an essential component in the motors, wiring, radiators, connectors, brakes, and bearings used in cars and trucks. The average car contains 1.5 kilometers (0.9 mile) of copper wire, and the total amount of copper ranges from 20 kilograms (44 pounds) in small cars to 45 kilograms (99 pounds) in luxury and hybrid vehicles.
Ancient Uses of Copper
As in ancient times, copper remains a component of coinage used in many countries, but many new uses have been identified. One of copper’s more recent applications includes its use in frequently touched surfaces (such as brass doorknobs), where copper’s antimicrobial properties reduce the transfer of germs and disease. Semiconductor manufacturers have also begun using copper for circuitry in silicon chips, which enables microprocessors to operate faster and use less energy. Copper rotors have also recently been found to increase the efficiency of electric motors, which are a major consumer of electric power.
What Properties Make Copper Useful?
The excellent alloying properties of copper have made it invaluable when combined with other metals, such as zinc (to form brass), tin (to form bronze), or nickel. These alloys have desirable characteristics and, depending on their composition, are developed for highly specialized applications. For example, copper-nickel alloy is applied to the hulls of ships because it does not corrode in seawater and reduces the adhesion of marine life, such as barnacles, thereby reducing drag and increasing fuel efficiency. Brass is more malleable and has better acoustic properties than pure copper or zinc; consequently, it is used in a variety of musical instruments, including trumpets, trombones, bells, and cymbals.
Types of Copper Deposits
Copper occurs in many forms, but the circumstances that control how, when, and where it is deposited are highly variable. As a result, copper occurs in many different minerals. Chalcopyright is the most abundant and economically significant of the copper minerals.
Research designed to better understand the geologic processes that produce mineral deposits, including copper deposits, is an important component of the USGS Mineral Resources Program. Copper deposits are broadly classified on the basis of how the deposits formed. Porphyry copper deposits, which are associated with igneous intrusions, yield about two-thirds of the world’s copper and are therefore the world’s most important type of copper deposit. Large copper deposits of this type are found in mountainous regions of western North and South America.
Another important type of copper deposit-the type contained in sedimentary rocks-accounts for approximately one-fourth of the world’s identified copper resources. These deposits occur in such areas as the central African copper belt and the Zechstein basin of Eastern Europe.
Individual copper deposits may contain hundreds of millions of tons of copper-bearing rock and commonly are developed by using open-pit mining methods. Mining operations, which usually follow ore discovery by many years, often last for decades. Although many historic mining operations were not required to conduct their mining activities in ways that would reduce their impact on the environment, current Federal and State regulations do require that mining operations use environmentally sound practices to minimize the effects of mineral development on human and ecosystem health.
USGS mineral environmental research helps characterize the natural and human interactions between copper deposits and the surrounding aquatic and terrestrial ecosystems. Research helps define the natural baseline conditions before mining begins and after mine closure. USGS scientists are investigating climatic, geologic, and hydrologic variables to better understand the resource-environment interactions
What is a Maar?
A maar is a shallow volcanic crater with steep sides that is surrounded by tephra deposits. The tephra deposits are thickest near the crater and decrease with distance from the crater.
A maar is formed by one or more underground explosions that occur when hot magma comes into contact with shallow ground water to produce a violent steam explosion. These explosions crush the overlying rocks and launch them into the air along with steam, water, ash and magmatic material. The materials usually travel straight up into the air and fall back to Earth to form the tephra deposits that surround the crater. If the tephra lithifies, it will become an igneous rocks known as tuff.
|If tephra surrounding a maar lithifies, it will become a rock known as “tuff.” Tuff is composed of rock fragments and large pieces of tephra in a matrix of volcanic ash. Image by Roll-Stone of Wikimedia.|
The crater floor of a maar is usually below the original ground surface. After the eruption, an inflow of groundwater often turns the crater into a shallow lake.
Most maars are a few hundred to a thousand meters in diameter and less than one hundred meters in depth. The largest maars, located on the Seward Peninsula of Alaska, are up to 8000 meters across and up to 300 meters in depth. See Google map at right.
How Common are Maars?
Maars are more numerous than most people realize. After cinder cones, maars are the second most common volcanic landform. If you search the Smithsonian Institution’s Global Volcanism Program database, you will be able to find hundreds of maars.
Maars are underrepresented as volcanic landscape features because they are small in size and lack rocky vertical development that would make them resistant to weathering and erosion. Because they are relatively small, shallow depressions, they can be easily filled with sediment and not recognized as volcanic features.
The explosions that form a maar are known as phreatic explosions. They are driven in part by the enormous and instantaneous volume change that occurs when water flashes into steam.
When suddenly heated, one cubic meter of water converts into 1,600 cubic meters of steam. If this happens below Earth’s surface, the result can be a vertical eruption of steam, water, ash, volcanic bombs and rock debris. The volcanic cones produced by these eruptions are made up mostly of ejecta and are usually of very low relief – only a few tens of meters.
Some magmas contain enormous amounts of dissolved gas sometimes up to several percent gas by weight. This gas is under very high confining pressure because the magma is below Earth’s surface. During the formation of a maar, the rock above the magma chamber is usually blasted away. This suddenly reduces the confining pressure on the magma and its dissolved gas. The sudden pressure reduction allows an immediate and violent expansion of the dissolved gas. The magma then degasses like a can of shaken beer when the pull tab is removed. When degassing magma adds to the explosive force, the eruption is known as “phreatomagmatic”.
Not all phreatic and phreatomagmatic eruptions occur from the interaction of hot magma with groundwater. Other water sources include lakes, streams, the ocean, or melting permafrost.
Maars are usually formed by multiple explosions. Initially there can be simultaneous explosions at multiple depths. After the initial explosions, groundwater from surrounding lands begins draining towards the crater and fuels additional blasts. These continue until the supply of local groundwater is depleted or the magma source has been depleted or cooled. The 1977 eruption at the East Ukinrek Maar Crater, shown in the photos at the top of this page, consisted of a series of explosions that persisted for a period of ten days.
The Largest Known Maar
The largest known maar on Earth is Devil Mountain Maar Lake, located on the northern part of the Seward Peninsula of Alaska. It was produced by a hydromagmatic eruption that occurred about 17,500 years ago. The blast spread tephra over an area of about 2,500 square kilometers. The tephra is several tens of meters thick near the maar and decreases with distance away from the maar. You can explore five of the world’s largest maars in the Google satellite image in the right column of this page.
Igneous, Sedimentary vs Metamorphic Rocks
The main difference between Igneous, Sedimentary and Metamorphic rocks, is the way that they are formed, and their various textures.
Igneous rocks are formed when magma (or molten rocks) cool down, and become solid. High temperatures inside the crust of the Earth cause rocks to melt, and this substance is known as magma. Magma is the molten material that erupts during a volcano. This substance cools down slowly, and causes mineralization to take place. Gradually, the size of the minerals increase until they are large enough to be visible to the naked eye. Igneous rocks are mostly formed beneath the Earth’s surface.
The texture of Igneous rocks can be referred to as Phaneritic, Aphaneritic, Glassy (or vitreous), Pyroclastic or Pegmatitic. Examples of Igneous Rocks include granite, basalt and diorite.
Sedimentary rocks are usually formed by sedimentation of the Earth’s material, and this normally occurs inside water bodies. The Earth’s material is constantly exposed to erosion and weathering, and the resulting accumulated loose particles eventually settle, and form Sedimentary rocks. Therefore, one can say, that these types of rocks are formed slowly from the sediments, dust and dirt of other rocks. Erosion takes place due to wind and water. After thousands of years, the eroded pieces of sand and rock settle, and become compacted to form a rock of their own.
Sedimentary rocks range from small clay-size rocks to huge boulder-size rocks. The textures of Sedimentary rocks are mainly dependent on the parameters of the clast, or the fragments of the original rock. These parameters can be of various types, such as surface texture, round, spherical or in the form of grain. The most common type of Sedimentary rock is the Conglomerate, which is caused by the accumulation of small pebbles and cobbles. Other types include shale, sandstone and limestone, which is formed from clastic rocks and the deposition of fossils and minerals.
Metamorphic rocks are the result of the transformation of other rocks. Rocks that are subjected to intense heat and pressure change their original shape and form, and become Metamorphic rocks. This change in shape is referred to as metamorphism. These rocks are commonly formed by the partial melting of minerals, and re-crystallization. Gneiss is a commonly found Metamorphic rock, and it is formed by high pressure, and the partial melting of the minerals contained in the original rock.
Metamorphic rocks have textures like slaty, schistose, gneissose, granoblastic or hornfelsic. Examples of these types of rocks include slate, gneiss, marble, and quartzite, which occurs when re-crystallization changes the shape and form of an original rock formation.
1.Igneous rocks are formed when magma (or molten rocks) have cooled down and solidified. Sedimentary rocks are formed by the accumulation of other eroded substances, while Metamorphic rocks are formed when rocks change their original shape and form due to intense heat or pressure.
2.Igneous rocks are commonly found inside the Earth’s crust or mantle, while Sedimentary rocks are usually found in water bodies (sea, oceans etc.). Metamorphic rocks are found on the Earth’s surface.
3.Igneous rocks can be an important source of minerals, and Sedimentary rocks, or their bedding structure, is mostly used in civil engineering; for the construction of housing, roads, tunnels, canals etc. Geologists study the geological properties of Metamorphic rocks, as their crystalline nature provides valuable information about the temperatures and pressures within the Earth’s crust.
4.Examples of Igneous rocks include granite and basalt, while examples of Sedimentary rocks include shale, limestone and sandstone. Common examples of Metamorphic rocks are marble, slate and quartzite.
WHAT ARE METEORITES?
The first in a series of articles by Geoffrey Notkin, Aerolite Meteorites
What are Meteors?
Every year hundreds of hopeful people contact me because they believe that an unusual or out-of-place rock they have found is a meteorite. I frequently receive emails which contain an amusing but impossible statement along the lines of: “I think I’ve found a meteor.”
In order to appreciate the humor inherent in this sentence we must first understand the difference between meteors and meteorites. Meteor is the scientific name for a shooting star: the light emitted as fragments—usually rather small—of cosmic material which we sometimes see at night, burning high up in the earth’s atmosphere. The bright, and typically very short-lived flame, is caused by atmospheric pressure and friction as pieces of extraterrestrial material become so hot they literally incandesce, as does the air around them. Manned spacecraft such as NASA’s space shuttle and the Mercury, Gemini, and Apollo capsules experienced similar heating during re-entry into our atmosphere, which is why they employ heat shields to protect the astronauts and cargoes inside.
There are a number of periodic meteor showers visible each year in the night sky: the Perseids in August, and the Leonids in November usually being the most interesting to observe. The annual meteor showers are the result of our planet passing through debris trails left by comets. The meteors we see during those annual displays are typically small pieces of ice which rapidly burn up in the atmosphere and never make it to the surface of our planet.
An sporadic is a meteor which is not associated with one of the periodic showers and the majority of those meteors also burn up entirely in the atmosphere which acts as a shield, protecting us earthbound humans from falling space debris. Any portion of a meteor which does survive its fiery flight and falls to the surface of the earth is called a meteorite. So, meteorite scientists and hunters understandably chuckle to themselves when a hopeful person claims to have discovered a meteor. The excited people who ask me to help them identify a strange rock should actually be saying: “I think I’ve found a meteorite.”
A polite and charming lady once telephoned the Aerolite Meteorites office and asked if we had, for sale, any meteorites from the constellation of Castor and Pollux. I explained to her that most—or possibly all—meteorites found on earth originate from within the Asteroid Belt between Mars and Jupiter, but there is a chance that some meteorites come to us from farther afield. It has been theorized that rare carbon-bearing meteorites known as a carbonaceous chondrites—such as Murchison which fell in Victoria, Australia in 1969—may be the remnants of a comet nucleus, but that remains conjecture. The stone meteorite Zag, which was seen to fall in the Western Sahara in 1998 and later recovered by nomads, contains water and so a slightly more fanciful but intriguing theory developed which suggests that large meteorites may have carried both water and amino acids (the so-called “building blocks of life”) to our planet in the distant past.
What are Meteorites?
Meteorites are rocks, usually containing a great deal of extraterrestrial iron, which were once part of planets or large asteroids. These celestial bodies broke up, or perhaps never fully formed, millions or even billions of years ago. Fragments from these long-dead alien worlds wandered in the coldness of space for great periods of time before crossing paths with our own planet. Their tremendous terminal velocity, which can result in an encounter with our atmosphere at a staggering 17,000 miles per hour, produces a short fiery life as a meteor. Most meteors burn for only a few seconds, and that brief period of heat is part of what makes meteorites so very unique and fascinating. Fierce temperatures cause surfaces to literally melt and flow, creating remarkable features which are entirely unique to meteorites, such as regmaglypts (“thumbprints”), fusion crust, orientation, contraction cracks, and rollover lips. These colorful terms will be discussed and examined in future editions of Meteorwritings.
Meteorites: Very Rare and Very Old
Meteorites are among the rarest materials found on earth and are also the oldest things any human has ever touched. Chondrules—small, colorful, grain-like spheres about the size of a pin head—are found in the most common type of stone meteorite, and give that class its name: the chondrites. Chondrules are believed to have formed in the solar nebula disk, even before the planets which now inhabit our solar system. Our own planet was probably once made up of chondritic material, but geologic processes have obliterated all traces of the ancient chondrules. The only way we can study these 4.6 billion year old mementoes from the early days of the Solar System is by looking at meteorites. And so meteorites become valuable to scientists as they are nothing less than history, chemistry, and geology lessons from space.
Sand isn’t a boring material if you know what you are looking at!
|Highly rounded sand grains from the Gobi Desert of Mongolia. Wind-blown sand sustains repeated tiny impacts as it bounces along Earth’s surface. These impacts gradually abrade sharp protrusions from the grains and give their surface a “frosted” luster. The width of this view is approximately 10 millimeters. Photograph by Siim Sepp, used here under a Creative Commons License.|
Thinking About Sand
Sand is a common material found on beaches, deserts, stream banks and other landscapes worldwide. In the mind of most people, sand is a white or tan, fine-grained, granular material. However, sand is much more diverse – even beyond the pink sand beaches of Bermuda or the black sand beaches of Hawaii. These are just a few of the many types of sand.
What is Sand?
The word “sand” is actually used for a “particle size” rather than for a “material.” Sand is a loose, granular material with particles that range in size between 1/16 millimeter and 2 millimeters in diameter. It can be composed of mineral material such as quartz,orthoclase or gypsum; organic material such as mollusk shells, coral fragments or radiolarian tests; or rock fragments such asbasalt, pumice or chert. Where sand accumulates in large quantities, it can be lithified into a sedimentary rock known assandstone.
Most sands form when rock materials are broken down by weathering and transported by a stream to their place of deposition. A few types form when the shell or skeletal materials of organisms are broken up and transported. A few rare sands are formed chemically from materials dissolved or suspended in sea water.
Unusual Types of Sand
This page shows photos of a few types of sand that can be found worldwide. Most of the examples here are not typical. They are unusual types of sand that might only be found in a few locations worldwide. These unusual sands are a product of the types of material from which they are derived, the methods used to transport them, the chemical environment of their deposition site, and numerous other factors. After examining these photos you will probably conclude that sand can be a very diverse and interesting material.
Thanks to the many photographers who shared their photos through a Creative Commons License. Please see an attribution in the caption of each photo. A person would have to travel the world to get a collection of photos like this.
REE – Rare Earth Elements and their Uses
The demand for rare earth elements has grown rapidly, but their occurrence in minable deposits is limited.
|This chart shows a history of rare earth element production, in metric tons of rare earth oxide equivalent, between 1950 and 2015. It clearly shows the United States’ entry into the market in the mid-1960s when color television exploded demand. When China began selling rare earths at very low prices in the late-1980s and early-1990s, mines in the United States were forced to close because they could no longer make a profit. When China cut exports in 2010, rare earth prices skyrocketed. That motivated new production in the United States, Australia, Russia, Thailand, Malaysia, and other countries.|
What Are Rare Earth Elements (REEs)?
Rare earth elements are a group of seventeen chemical elements that occur together in the periodic table (see image at right). The group consists of yttrium and the 15 lanthanide elements (lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium). Scandium is found in most rare earth element deposits and is sometimes classified as a rare earth element. The International Union of Pure and Applied Chemistry includes scandium in their rare earth element definition.
The rare earth elements are all metals, and the group is often referred to as the “rare earth metals.” These metals have many similar properties and that often causes them to be found together in geologic deposits. They are also referred to as “rare earth oxides” because many of them are typically sold as oxide compounds.
Uses of Rare Earth Elements
Rare earth metals and alloys that contain them are used in many devices that people use every day such as computer memory, DVDs, rechargeable batteries, cell phones, catalytic converters, magnets, fluorescent lighting and much more.
During the past twenty years, there has been an explosion in demand for many items that require rare earth metals. Twenty years ago there were very few cell phones in use, but the number has risen to over 7 billion in use today. The use of rare earth elements in computers has grown almost as fast as cell phones.
Many rechargeable batteries are made with rare earth compounds. Demand for the batteries is being driven by demand for portable electronic devices such as cell phones, readers, portable computers, and cameras.
Several pounds of rare earth compounds are in batteries that power every electric vehicle and hybrid-electric vehicle. As concerns for energy independence, climate change and other issues drive the sale of electric and hybrid vehicles, the demand for batteries made with rare earth compounds will climb even faster.
Rare earths are used as catalysts, phosphors, and polishing compounds. These are used for air pollution control, illuminated screens on electronic devices, and the polishing of optical-quality glass. All of these products are expected to experience rising demand.
Other substances can be substituted for rare earth elements in their most important uses; however, these substitutes are usually less effective and costly.
From the 1950s until the early 2000s, cerium oxide was a very popular lapidary polish. It was inexpensive and very effective. The recent price increases have almost eliminated the use of cerium oxide in rock tumbling and the lapidary arts. Other types of polish, such as aluminum and titanium oxide, are now used in its place.
Critical Defense Uses
Rare earth elements play an essential role in our national defense. The military uses night-vision goggles, precision-guided weapons, communications equipment, GPS equipment, batteries and other defense electronics. These give the United States military an enormous advantage. Rare earth metals are key ingredients for making the very hard alloys used in armored vehicles and projectiles that shatter upon impact.
Substitutes can be used for rare earth elements in some defense applications; however, those subsitutes are usually not as effective and that diminishes military superiority. Several uses of rare earth elements are summarized in the table below.
Are These Elements Really “Rare”?
Rare earth elements are not as “rare” as their name implies. Thulium and lutetium are the two least abundant rare earth elements – but they each have an average crustal abundance that is nearly 200 times greater than the crustal abundance of gold. However, these metals are very difficult to mine because it is unusual to find them in concentrations high enough for economical extraction.
The most abundant rare earth elements are cerium, yttrium, lanthanum and neodymium. They have average crustal abundances that are similar to commonly used industrial metals such as chromium, nickel, zinc, molybdenum, tin, tungsten and lead. Again, they are rarely found in extract able concentrations.
History of Rare Earth Production and Trade
Before 1965 there was relatively little demand for rare earth elements. At that time, most of the world’s supply was being produced from placer deposits in India and Brazil. In the 1950s, South Africa became the leading producer from rare earth bearingmonazite deposits. At that time, the Mountain Pass Mine in California was producing minor amounts of rare earth oxides from a Precambrian carbonatite.
Color Television Ignites Demand
The demand for rare earth elements saw its first explosion in the mid-1960s, as the first color television sets were entering the market. Europium was the essential material for producing the color images. The Mountain Pass Mine began producing europium from bastnasite, which contained about 0.1% europium. This effort made the Mountain Pass Mine the largest rare earth producer in the world and placed the United States as the leading producer.
China Enters the Market
China began producing noteable amounts of rare earth oxides in the early 1980s and became the world’s leading producer in the early 1990s. Through the 1990s and early 2000s, China steadily strengthened its hold on the world’s rare earth oxide market. They were selling rare earths at such low prices that the Mountain Pass Mine and many others throughout the world were unable to compete and stopped operation.
Defense and Consumer Electronics Demand
At the same time, world demand was skyrocketing as rare earth metals were designed into a wide variety of defense, aviation, industrial and consumer electronics products. China capitalized on its dominant position and began restricting exports and allowing rare earth oxide prices to rise to historic levels.
China as the Largest Rare Earth Consumer
In addition to being the world’s largest producer of rare earth materials, China is also the dominant consumer. They use rare earths mainly in manufacturing electronics products for domestic and export markets. Japan and the United States are the second and third largest consumers of rare earth materials. It is possible that China’s reluctance to sell rare earths is a defense of their value-added manufacturing sector.
China’s Apex of Production Dominance?
The Chinese dominance may have peaked in 2010 when they controlled about 95% of the world’s rare earth production and prices for many rare earth oxides had risen over 500% in just a few years. That was an awakening for rare earth consumers and miners throughout the world. Mining companies in the United States, Australia, Canada and other countries began to reevaluate old rare earth prospects and explore for new ones.
High prices also caused manufacturers to do three things: 1) seek ways to reduce the amount of rare earth elements needed to produce each of their products; 2) seek alternative materials to use in place of rare earth elements; and, 3) develop alternative products that do not require rare earth elements.
This effort has resulted in a decline in the amounts of rare earth materials used in some types of magnets and a shift from rare earth lighting products to light-emitting diode technology. In the United States, the average consumption of rare earths per unit of manufactured product has decreased but the demand for more products manufactured with rare earth elements has increased. The result has been higher consumption.
China Buying Resources Outside of China
Chinese companies have been purchasing rare earth resources in other countries. In 2009 China Non-Ferrous Metal Mining Company bought a majority stake in Lynas Corporation, an Australian company that has one of the highest outputs of rare earth elements outside of China. They also purchased the Baluba Mine in Zambia.