What makes pyrite

If you were to rub the mineral vigorously with a hard object then if pyrite it will give off a sulphurous smell like rotten eggs but if gold no odour will be apparent. As well, if struck with a steel hammer gold will flatten or change shape without breaking but pyrite will give off sparks.

Chalcopyrite looks similar to pyrite but it is softer and can be scratched with a knife. It is a very brassy yellow, often with a bronze or iridescent tarnish whereas pyrite is simply a brassy yellow. As well, pyrite is slightly heavier than pyrite. The name marcasite is derived from the Arabic word for pyrite.

This mineral is a common and attractive mineral. It has the same chemical composition as pyrite, but it has a different crystallization system, making is a pseudomorph of pyrite. Without proper analysis aggregates of iron sulphide may be wrongly labelled by dealers. Crystal habits include the tabular, bladed or prismatic forms. Picher, Oklahoma, USA. Over a period of years, marcasite will oxidize in collection.

This process frees sulphur which frees sulphuric acid. The acid will then attack a paper label or even a cardboard box that the mineral might be kept in. Over a period of decades, most specimens will have disintegrated into a white dust along with deteriorated paper scraps. A sulphur smell will be released during this reaction contaminating other sulphide minerals nearby.

Marcasite is common worldwide. It occurs mainly in sedimentary deposits in low temperature ore veins, as well as in skarn metamorphic deposits.

Marcasite is more brittle than gold. It is also lighter and is a brassy yellow mineral with a greenish tint at times or possibly a multi-coloured tarnish which results from oxidation. Marcasite is difficult to distinguish from pyrite when there is a lack of distinctive crystal habits. As well, marcasite is a brassy yellow with a greenish tint at times. A multi-coloured tarnish may exist which is the result of oxidation.

It is important to note that marcasite is too soft to be used in jewellery. For this reason, marcasite jewellery is actually made from pyrite, contrary to the impression one gets from its name. The Incas are the earliest known civilization to use marcasite in jewellery. Notable pieces have been found in several burial chambers.

As well, marcasite was used by the Incas as mirrors, in sun-worship rituals and as a means of seeing into the future. During the Georgian period the Swiss began to produce marcasite for the European market to bypass the Sumptuary Laws which forbade the use of diamond by all but the most aristocratic. When cut in a pyramid shape with a flat back the marcasite had a brilliance resembling diamond. Early cut steel was used in the same way.

Arsenopyrite is named for the minerals chemical composition. It is silver-white to steel-gray in colour with a greyish black streak. The mineral tarnishes dark gray but occasionally also an iridescent pink. Rarely is it seen in igneous basalt rocks. Akerman Mine, Madoc, Ontario.

Notice the small red circle point out the rectangular shape of the crystals. Chromate Copper Arsenate CCA has been used to treat wood to prevent rotting in lumber designated for use outdoors since the s. This treatment was used on the majority of wood from the s until The arsenic in the wood is hazardous and is in fact a known human carcinogen. Exposure can cause cancer of the lung, bladder, skin, kidney, prostate and nasal passage as well as leading to nerve damage, dizziness, diabetes and changes in hormone function.

The chemicals in the CCA —treated wood have been shown to leach into the environment and can transfer to the skin when people touch the wood. Sulfuric acid is a relatively recent manufactured chemical. Prior to this, the important analogous chemical substances were the sulfate salts of iron, copper, and aluminum, known to the ancients as the vitriols. These occurred in the lists of minerals compiled by the Sumerians 4, years ago. They were used as mordants in the dyeing industry.

In order for natural dyes to be fixed in the cloth—and not be washed out during the next rainy day—it is necessary to treat the cloth with a mordant.

The mordants widely used in dyeing were solutions of the vitriols. The demand for vitriols could not be satisfied from natural supplies, and industries developed to manufacture this substance from pyrite. The production of one mordant, pure alum, from pyrite has been described as the point of origin of the modern chemical industry, because the process required not only the manufacture of a chemical substance but also its purification. The manufacture of artificial drugs—in contrast to the use of natural remedies—can be traced back to pyrite and strike-a-lights.

It is not a big step to drop pyrite from a strike-a-light into the fire. The result is the formation of sulfur oxide gases with their characteristic burnt smell. These sulfur oxide gases, apart from being poisonous in high doses, can clear clogged-up noses and are very useful in fumigation.

Pyrite is a major source of sulfur, the basic constituent of sulfuric acid, which is one of the most important industrial chemicals, and made in greater amounts each year than any other manufactured chemical.

One of the earliest descriptions of the medicinal use of sulfur was in The Pharmacopeia of the Heavenly Husbandsman, compiled in the Western Han period BCE—24 CE , which cataloged the medicines invented some 3, years earlier by the legendary emperor Shen Nong.

Medical sulfur had to be produced from pyrite in the absence of deposits of natural sulfur. Sulfur was used mainly in creams, to alleviate conditions such as scabies, ringworm, psoriasis, eczema, and acne. The mechanism of action is unknown—although sulfur does oxidize slowly to sulfurous acid, which in turn through the action of sulfite acts as a mild reducing and antibacterial agent.

The use of alum in medicine has been documented for more than 2, years since the Babylonians listed it in one of the first pharmacopeias. The main medicinal use of alum was, as it still is today, as an astringent to improve wound healing.

The modern styptic used to close up razor nicks occurring after wet shaving is alum-based. It helps reduce swelling of the skin around healing sores. It has also been used as an emetic to treat someone who has ingested a poison. We have seen that pyrite is the raw material from which sulfuric acid can be made, and a major use of sulfuric acid in modern economies is in the production of fertilizers.

About 60 percent is currently consumed for fertilizer manufacture, especially superphosphates, ammonium phosphate, and ammonium sulfates. During the early part of the Industrial Revolution, sulfur in Europe was sourced from natural sulfur deposits associated with volcanic fumaroles in Sicily.

In the Sicilian deposits came into the hands of a French company, which raised the price threefold. This led to other countries reverting to pyrite as a source of sulfur. Roasting of pyrite produces sulfur oxide gases, and these can be dissolved in water to produce sulfuric acid. Byproducts of the process include copper metal from the pyrite and an iron-based slag that is used in road-building.

It has been estimated that the population of Great Britain was constrained to around 6 million in preindustrial times due to the limitations of agricultural productivity. This compares with more than 60 million today. The excess 54 million people are fed by postindustrial technological advances. This step increase in agricultural productivity was fueled by the development of industrial fertilizers.

This, in turn, caused a consequent exponential increase in the demand for sulfuric acid, sulfur, and pyrite. Pyrite reserves are distributed throughout the world, and known deposits have been mined in about 30 countries. Currently global pyrite production is about 14 million tons per year, and about 85 percent of this is in China. This amounts to around 10 percent of the total world sulfur production. Most of this sulfur is used in sulfuric acid manufacture, and most of the sulfuric acid is used to make fertilizers.

In this context, pyrite continues to be a major factor in food production. The reason is that the science of crystallography is little appreciated by the general public or understood by fellow scientists, apart from the crystallographers themselves. And yet this science has won more Nobel Prizes over the past century than any other subdiscipline. Of the Nobel Prizes in science and medicine that have been awarded since , more than have directly involved crystallography.

The golden crystals of pyrite have played a key role in the development of crystallography, ultimately permitting atoms themselves to be counted, imaged, and probed. If you look at the surface of a CD or DVD disk at an angle, you will see a shimmering spectrum of colors on the surface of the disk as bands of luminous greens and blues seem to radiate out from the center of the disk.

The grooves on the disk are diffracting the light that is being reflected from its silver surface. Diffraction occurs when a wave encounters an obstacle. As the wave hits an object, new waves are produced at all points along the wave front. These waves propagate spherically, and thus light can appear to bend as it passes an object.

If there is a narrow slit, light will appear to bend around both edges of the slit. And if the width of the slit approaches the wavelength of the light, the light waves emitted from the slit edges will either be in phase or out of phase: If the diffracted waves are in phase that is, their peaks and troughs are coincident , then the resultant intensity is increased; if the diffracted waves are out of phase, then the peaks are canceled out by the troughs and no light is seen.

In the case of light, the troughs and ridges are represented by a series of bands. These depend on the wavelength of the incident beam and the density of the slits in the object. The diffraction effect is seen on the fine grooves of a CD disk but not on a grill, for example. In a typical diffraction grating, the number of slits ranges from a few tens to a few thousand per millimeter.

Note that because there is a relationship between the wavelength of light and the slit width, each wavelength of the incident beam is sent in a slightly different direction. This can produce a spectrum of colors from white light illumination, visually similar to the operation of a glass prism; this is the shimmering, multicolored effect on the CD surface.

The upshot of all this is that by measuring the angle of the emitted light from a diffraction grating and its wavelength, we can calculate the size and number of the slits in the grating that produced the spectrum. 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. Gold and pyrite form under similar conditions and occur together in the same rocks.

In some deposits small amounts of gold occur as inclusions and substitutions within pyrite. Some pyrites can contain 0. Although this is a tiny fraction of the ore, the value of gold is so high that the pyrite might be a worthwhile mining target.

If pyrite contains 0. That is not a guaranteed money-maker. It depends upon how efficiently the gold can be recovered and the cost of the recovery process. Pyrite Framboid: One of the most interesting crystal habits of pyrite is the "framboid. This is a framboid from the Waynesburg coal of northern West Virginia. It is a sphere about 15 microns in diameter that is composed of cubic crystals of pyrite about one micron on a side.

Sulfur occurs in coal in three different forms: 1 organic sulfur, 2 sulfate minerals, and 3 sulfide minerals mostly pyrite with minor amounts of marcasite. When the coal is burned, these forms of sulfur are converted into sulfur dioxide gas and contribute to air pollution and acid rain unless they are removed from the emissions. The sulfide minerals in coal and its surrounding rocks can produce acid mine drainage.

Before mining, these minerals are deep within the ground and below the water table where they are not subject to oxidation. During and after mining the level of the water table often falls, exposing the sulfides to oxidation. 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.