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Pyrite
Current inventory:  0 gems
 

Chemistry:  FeS₂  [Iron Sulfide]

Discovered in Prehistory;   IMA status: Valid (pre-IMA; Grandfathered).
Pyrite is named from the Greek, pyrites lithos, for "stone which strikes fire," in allusion to the sparking produced when iron is struck by a lump of pyrite.

Classification

Mineral Classification:

Sulfides

Strunz 8th Ed. ID:

2/D.17-30

Nickel-Strunz 10th Ed. ID:

2.EB.05a

2 : SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulfantimonites, sulfbismuthites, etc.)
E : Metal Sulfides, M: S <= 1:2
B : M:S = 1:2, with Fe, Co, Ni, PGE, etc.

Related to:

Pyrite Group. Pyrite - Cattierite Series. Dimorphous with Marcasite.

Crystal Data

Crystallography:

Isometric - Diploidal

Crystal Habit:

Typically cubic, pyritohedral, octahedral, and combinations of these and other forms, to 25 cm or more. Striated conforming to pyritohedral symmetry; may be elongated to acicular. Commonly granular, globular, framboidal, stalactitic.

Twinning:

On [110], interpenetrating (Iron Cross Law). Twin axis [001] and twin plane [011], penetration and contact twins.

Physical Properties

Cleavage:

[100] Poor, [110] Poor; partings on [011] and [111]

Fracture:

Conchoidal to Uneven

Tenacity:

Brittle

Hardness (Mohs):

6.0 - 6.5

Density:

4.80 - 5.02 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Other:

Paramagnetic; a semiconductor. Magnetic after heating. Some fine-grained pyrite is metastable and may alter to melanterite, which contains sulfuric acid. Always wash hands after handling, especially decrepitated material. Avoid inhaling dust when handling or breaking. Never lick or ingest.

Optical Properties

Color:

Pale Brass Yellow; tarnishes darker and iridescent

Transparency:

Opaque

Luster:

Metallic

Refractive Index:

None (opaque)

Birefringence:

None (opaque)

Dispersion:

None (opaque)

Pleochroism:

None

Anisotrophism:

Rarely

Occurances

Geological Setting:

Formed under a wide variety of conditions. In hydrothermal veins as very large bodies, as magmatic segregations, as an accessory mineral in igneous rocks, in pegmatites; in contact metamorphic deposits, also in metamorphic rocks; as diagenetic replacements in sedimentary rocks.

Common Associations:

Arsenopyrite, Barite, Calcite, Chalcopyrite, Fluorite, Galena, Hematite, Marcasite, Pyrrhotite, Quartz, Sphalerite;  many sulfides and sulfosalts.

Common Impurities:

Ni, Co, As, Cu, Zn, Ag, Au, Tl, Se, V

Type Locality:

None (Prehistoric)

Year Discovered:

Prehistoric

View mineral photos:

Pyrite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Pyrite is also known as "Fool's Gold" since is often mistaken for Gold. Pyrite is a very common mineral, the most abundant of all sulfide minerals. It is so common that it is found in almost every type of geologic environment and in a vast number of forms and varieties. Pyrite is a polymorph of Marcasite, which means that it has the chemistry, FeS2, as Marcasite; but a different structure and therefore different symmetry and crystal shapes. Pyrite and Marcasite are often difficult to distinguish from one another due to their similar characteristics.

Marcasite is available from many localities worldwide.
 

  
Pyrite gems for sale:

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