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Pyrite

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Last updated date: 18th Apr 2024
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What is Pyrite?

Pyrite is a common mineral (also among the frequent natural sulphides and the most common disulfide) found in a wide range of geological formations, including sedimentary layers, hydrothermal veins, and metamorphic rocks. Pyrite's brassy-yellow metallic colour has made many people mistake it for gold, earning it the nickname the Fool's gold. Pyrite stone and pyrite quartz are easy to differentiate from gold because it is considerably lighter than gold. Yet, it is much more complicated and cannot be scratched with a fingernail or pocket blade.

Member of: Pyrite Group

Name: When it was struck with another mineral or metal in antiquity, Sparks flew from it, earning it the name "pyr" for "fire".


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Pyrite is a nickel-bearing mineral that forms a series with Vaesite and Bravoite is a nickel-bearing variation of Pyrite. 

Pyrite forms a series with Cattierite and usually contains minor cobalt. Metal nanoparticles are responsible for the majority of the foreign metal concentration in Pyrite. In a damp atmosphere, Pyrite will slowly oxidize and release sulfuric acid generated during the process. Pyrite developed as sedimentary concretions tends to dissolve quickly, although well-crystallized specimens are often very stable.


Pyrite Properties

Physical Properties

  • Lustre: Metallic

  • Transparency: Opaque

  • Colour: Pale brass-yellow

  • Streak: Greenish-black

  • Hardness level: 6 - 6½ on Mohs scale

  • Hardness Data: Measured

  • Tenacity: Brittle

  • Cleavage: Poor/Indistinct; Indistinct on {001}.

  • Fracture: Irregular/Uneven, Conchoidal

  • Density: 4.8 - 5 g/cubic centimeters (Measured); 5.01 g/cubic centimeters (Calculated)

Chemical Properties

  • Formula: FeS2

  • Elements listed: Fe, S 

  • Common Impurities: Ni,Co,As,Cu,Zn,Ag,Au,Tl,Se,V

Crystallography of Pyrite

  • Crystal System: Isometric

  • Class (H-M): m3 (2/m 3) - Diploidal

  • Space Group: Pa3

  • Setting: Pa3

  • Cell Parameters: a = 5.417 Å

  • Unit Cell V: 158.96 ų (Calculated from Unit Cell)

  • Z: 4

  • Morphology: Typical faces are cubic or pyritohedral (pentagonal dodecahedral); however, octahedral combinations are also prevalent. Less typically octahedral, but more commonly granular, extensive, as well as occasionally radiating, discoidal, reniform, or globular.


Pyrite Types 

Argentian Pyrite

A pyrite rich in silver-rich, perhaps a mixture.

Arsenic-bearing Pyrite

A pyrite type, bearing arsenic. Not at all uncommon; mostly zoned.

Bravoite

A pyrite-bearing nickel.

Compare pyrite's nickel analogue, vaesite (NiS2), forming a full solid solution along with pyrite.

Cobalt-bearing Pyrite

A pyrite variety that bears cobalt.

Cobalt-nickel-pyrite (of Vernadsky)

A pyrite bearing Ni- and Co-.

Copper Pyrite

A pyrite type that bears copper.

 The copper pyrite formation with the substitution of Cu for Fe results in changes in Raman spectra and unit cell parameters. Copper pyrite formula - CuFeS2

Cupriferous Pyrite

A pyrite variety that contains some copper.

Gelpyrit

Iron disulphide's gel form, bearing arsenic.

Gold-bearing Pyrite

A pyrite variety, bearing gold.

Hengleinite

A bravoite bearing cobalt.

First described from Siegerland, Müsen, Germany, North Rhine-Westphalia.

Hepatic pyrite

Liver-coloured marcasite or pyrite.

Nickelian Pyrite

A pyrite variety, bearing nickel.

Telaspyrine

Once considered a pyrite variety bearing tellurium, but probably a mixture.

Thallian Arsenian Pyrite

A pyrite variety, rich in Tl and As.


Identifying Pyrite

Pyrite hand specimens are usually straightforward to recognise. The mineral is always brassy yellow in colour, has a metallic sheen, and has a high specific gravity. Its streak is black, frequently with a tinge of green, and it is more challenging than other yellow metallic minerals. It is most commonly found in well-formed crystals in the shapes of cubes, pyritohedron, or octahedrons, with striated faces.

Marcasite, a dimorph of Pyrite with the same chemical composition but an orthorhombic crystal structure, is the only common mineral with attributes similar to Pyrite. The brassy yellow tint of marcasite differs from that of Pyrite. Instead, it's a soft brass colour with a tiny green tint to it. Marcasite is more brittle than Pyrite and has a lower specific gravity (4.8) than Pyrite.

Pyrite With Hematite: Pyrite with hematite from Rio Marina on the Italian island of Elba. The specimen measures about 3 inches (7.6 cm) in diameter.


Fool's Gold

It's easy to tell the difference between Pyrite and gold. With pin pressure, gold is exceedingly soft and will bend or dent. Pyrite is fragile, and pin pressure will cause thin sections to break. The streak of gold is yellow, while the streak of Pyrite is greenish-black. Gold has a much higher specific gravity than silver. You can avoid the "Fool's Gold" problem with some careful testing.

Massive Pyrite: Massive Pyrite from Rico, Colorado. The specimen measures about 3 inches (7.6 cm) in diameter.

Pyrite: Pyrite with hematite from Italy, Rio Marina, Isle of Elba. The specimen measures about 3 inches (7.6 cm) in diameter.

Studying with a collection of tiny specimens that you can hold, analyse, and notice their qualities is the most excellent approach to learning about minerals. The Geology.com Store offers inexpensive mineral collections.


Pyrite Uses

Pyrite is made up of iron and sulphur, but neither of these elements is found in large quantities in the mineral. Oxide ores, such as hematite and magnetite, are the most common sources of iron. These ores are found in far more significant quantities, the iron is easier to extract, and the metal is not tainted with sulphur, weakening it.

Pyrite was once a valuable resource for producing sulphur and sulfuric acid. The majority of sulphur is now obtained as a byproduct of the oil and gas industry. As a byproduct of gold production, some sulphur is still created from Pyrite.

Sometimes, this pyrite mineral is also used as a gemstone. It's made into beads, cabochons, faceted, and carved into different shapes. In the mid-to-late-1800s, this kind of jewellery was popular in the United States and Europe. Most of the jewellery stones were mistakenly labelled as "marcasite," but they are Pyrite. (Marcasite is a poor choice for jewellery because it oxidises quickly, and the oxidation products destroy anything it comes into contact with.) Pyrite is a poor choice for jewellery because it tarnishes quickly.)

FAQs on Pyrite

1.Describe Pyrite's application as an Ore of Gold?

The most common application of Pyrite is as gold ore. Gold and Pyrite are found in the same rocks and develop under comparable conditions. Small amounts of gold can be seen as inclusions and replacements inside Pyrite in some deposits.

Pyrites can contain up to 0.25 percent gold by weight. Although it only accounts for a small portion of the ore, the value of gold is so great that Pyrite might be a profitable mining target. If Pyrite contains 0.25 percent gold and the price of gold is \[\textrm{$1500}\] per troy ounce, one tonne of Pyrite will have nearly \[\textrm{$109,000}\] in gold. That isn't a sure-fire way to make money. It all relies on how well the gold can be recovered and how much the recovery procedure costs.

2.What are the essential elements for pyrite production?

A source of iron, a supply of sulphur, and an oxygen-poor environment are necessary for pyrite production in the sedimentary environment. This is frequently seen when the decomposing organic compounds are available. When organic matter decomposes, it consumes oxygen and releases sulphur. As a result, Pyrite is found most frequently and preferentially in dark-coloured organic-rich deposits like coal and black shale. Pyrite often replaces organic components such as plant detritus and shells to form intriguing pyrite fossils.