Why is pyrite valuable

This oxidation produces acid mine drainage which contaminates groundwater and streams. Mining also breaks the rocks above and below the coal. This creates more pathways for the movement of oxygenated waters and exposes more surface area to oxidation.

Pyrite crystals: Pyrite, cubic crystals in schist from Chester, Vermont. Specimen is approximately 4 inches 10 centimeters across. Crushed stone used to make concrete, concrete block, and asphalt paving materials must be free of pyrite. Pyrite will oxidize when it is exposed to air and moisture. That oxidation will result in the production of acids and a volume change that will damage the concrete and reduce its strength.

This damage can result in failure or maintenance problems. Pyrite should not be present in the base material, subsoil or bedrock under roads, parking lots, or buildings. Oxidation of pyrite can result in damage to pavement, foundations, and floors. In parts of the country where pyrite is commonly found, construction sites should be tested to detect the presence of pyritic materials. If pyrite is detected, the site can be rejected or the problem materials can be excavated and replaced with quality fill.

Pyrite fossils: Fossil ammonite in which the shell was replaced by pyrite. External view on left and cross-sectional view on right. External view by asterix and cross-sectional view by Henry Chaplin. Both images copyright iStockphoto.

The conditions of pyrite formation in the sedimentary environment include a supply of iron, a supply of sulfur, and an oxygen-poor environment. This often occurs in association with decaying organic materials. Organic decay consumes oxygen and releases sulfur. For this reason, pyrite commonly and preferentially occurs in dark-colored organic-rich sediments such as coal and black shale. The pyrite often replaces organic materials such as plant debris and shells to create interesting fossils composed of pyrite.

Article by: Hobart M. Find Other Topics on Geology. Atom probe tomography uses electrical pulses to peel atoms from a sample and observe them one by one. The method destroys the gold threads. But Fougerouse and his team investigated ways to extract the tiny traces of gold from the pyrite without destroying them.

The researchers found they could remove the nanothreads of gold with a technique called selective leaching, in which a fluid dissolves the precious metal out of the sample without damaging the pyrite. They found that this worked well because the same tiny nooks that trap the gold also act as channels that help the dissolved gold travel out.

The research was published June 24 in the journal Geology. In Max Laue reported that x-rays were diffracted by crystals. As with the CD and other diffraction gratings, the distances between the x-ray bands and their intensities depend on the distances between the atoms in the crystal.

X-rays exited in a pattern determined by the atomic structure. The technique was seized upon by W. Bragg and W. The Braggs realized that the angles and wavelength of the x-rays diffracted by a crystal would be functions of the positions of the planes of atoms in the crystal. Because there are several such planes in any crystal, this would enable the atomic structure of the crystal to be computed. Pyrite was one of the first crystalline materials investigated by the Braggs.

They used it to demonstrate that x-rays behaved in the same manner as light and not as a series of particles. In , W. Bragg succeeded in solving the pyrite structure and confirmed a theoretical mathematical model of pyrite. Pyrite helped support the foundations of x-ray crystallography, because it showed how the method could be used to determine the structure of a more complex substance.

Pyrite is a semiconductor; that is, it is neither a conductor like metal nor an insulator like most rocks. Semiconductors such as pyrite can switch between being a good conductor or insulator under the effects of electric fields or light, or by doping the material with traces of impurities. In pyrite, only a small amount of energy is required to release electrons from being chained to the atomic nuclei so that they can move freely in the material and conduct electricity.

In other words, a small amount of energy will switch pyrite from behaving like an insulator to behaving like a conductor. A suspension of tiny pyrite crystals might be sprayed onto solar panels like paint. Satisfying the increased demand for electricity will be one of the fundamental problems faced by humankind over the next 50 years. The obvious solution is to capture the energy from the Sun using solar panels. However, current silicon-based solar panels are expensive.

The energy cost, amortized over the year lifetime of the panel, is around twice as much as that of wind- and natural gas—generated electricity. This is where pyrite comes in as the most cost-efficient alternative solar panel material to conventional silicon. Pyrite absorbs times as much light as the present major solar cell material, silicon.

A thin layer of pyrite, just 0. Because only a very thin layer of pyrite is required to collect the sunlight, suspensions of tiny pyrite crystals, such as those that constitute the ubiquitous pyrite framboids, might be mixed in a solvent and sprayed onto panels like paint. Considerable research is going on worldwide at present to synthesize pyrite crystals and films with various compositions in order to produce an optimal solar energy collector. The other way to help resolve the world energy gap is to find a better way to store electricity.

Electric automobiles are wonderful, except for the fact that they are at present limited to a mile working distance and a hour charging cycle. Portable computers are fantastic—for eight hours until the battery runs out. Pyrite is a source material for sulfuric acid, and one use of it is in car batteries: It is the acid in the lead-acid battery.

These lead-acid batteries are still used in automobiles, even though the technology is ancient, because they are rechargeable. However, these lead-acid batteries are cumbersome and not suitable for many applications where a small solid-state battery is required.

The problem with these small batteries is that they are not especially powerful or, in many cases, rechargeable. There have been many recent advances in battery technology. One of the most familiar is the development of lithium batteries. In the Energizer series of lithium batteries, lithium metal is the anode the negative electrode , and pyrite is the cathode the positive electrode.

This pyrite has been ground down to 0. The battery works by a redox reaction whereby the lithium metal is oxidized to produce lithium sulfide and the pyrite is reduced to iron. The redox reaction produces electrons, which we use as electricity.

The lithium batteries are popular because they are relatively light, so the amount of energy per gram is optimized. At present these basically are not rechargeable, and the development of rechargeable lithium batteries is a major international target of technological research. Pyrite is an attractive material for the electronics industry: It is widely distributed, cheap, and readily available.

It has some environmental benefits in terms of the amount of energy required in transport and manufacture. All of these attributes are the same as those that originally placed pyrite at the core of early industrial development. It is interesting to speculate that the 21st century will see the burgeoning of a pyrite-driven electronics industry, just as earlier periods witnessed the development of pyrite-driven chemical, pharmaceutical, and explosives industries.

A microscopic image below shows gold occurring as tiny blebs entirely enclosed within a pyrite grain. In fact, pyrite is often associated with gold. The solutions in the Earth that transport iron and sulfur to form pyrite are also likely to transport other metals, including gold. Pyrite is slightly oxidized relative to other metal sulfide minerals. The slightly more oxidized environment in which pyrite precipitates also destroys the sulfide complexes that keep the gold in solution, and the gold precipitates as a metal.

For these reasons, most gold deposits in the world contain pyrite as a more or less abundant mineral. We wanted to look into an eco-friendlier way of extraction," Dr. Fougerouse said. Not only do the dislocations trap the gold, but they also behave as fluid pathways that enable the gold to be leached without affecting the entire pyrite. As pyrite is one of the most abundant minerals on Earth, a simple method that allows direct extraction of gold from it could be of great economic value.

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