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 

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.)