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"Fool's Gold" redirects here. For other uses, see Fool's Gold (disambiguation).
Pyrite
A mass of intergrown pyrite crystals
General
Category
Sulfide mineral
Chemical formula
iron disulfide (FeS2)
Strunz classification
02.EB.05a
Dana classification
2.12.1.1
Crystal symmetry
Isometric diploidal
Space group: Pa3
H-M symbol: 2/m3
Unit cell
a = 5.417 Å, Z=4
Identification
Color
Pale brass-yellow, tarnishes darker and iridescent
Crystal habit
Cubic, faces may be striated, but also frequently octahedral and pyritohedron. Often inter-grown, massive, radiated, granular, globular and stalactitic.
Crystal system
Isometric
Twinning
Penetration and contact twinning
Cleavage
Indistinct on {001}; partings on {011} and {111}
Fracture
Very uneven, sometimes conchoidal
Tenacity
Brittle
Mohs scale hardness
6–6.5
Luster
Metallic, glistening
Streak
Greenish-black to brownish-black
Diaphaneity
Opaque
Specific gravity
4.95–5.10
Fusibility
2.5–3 to a magnetic globule
Solubility
Insoluble in water
Other characteristics
paramagnetic
References
[1][2][3][4]
The mineral pyrite, or iron pyrite, is an iron sulfide with the formula FeS2. This mineral's metallic luster and pale brass-yellow hue have earned it the nickname fool's gold because of its resemblance to gold. The color has also led to the nicknames brass, brazzle and Brazil, primarily used to refer to pyrite found in coal.[5][6]
Pyrite is the most common of the sulfide minerals. The name pyrite is derived from the Greek πυρίτης (puritēs), "of fire" or "in fire",[7] in turn from πύρ (pur), "fire".[8] In ancient Roman times, this name was applied to several types of stone that would create sparks when struck against steel; Pliny the Elder described one of them as being brassy, almost certainly a reference to what we now call pyrite.[9] By Georgius Agricola's time, the term had become a generic term for all of the sulfide minerals.[10]
Pyrite is usually found associated with other sulfides or oxides in quartz veins, sedimentary rock, and metamorphic rock, as well as in coal beds, and as a replacement mineral in fossils. Despite being nicknamed fool's gold, pyrite is sometimes found in association with small quantities of gold. Gold and arsenic occur as a coupled substitution in the pyrite structure. In the Carlin–type gold deposits, arsenian pyrite contains up to 0.37 wt% gold.[11]
