Pyrite Value, Price, and Jewelry Information

By Mauro Cateb (Own work) [CC-BY-SA-3.0], via Wikimedia Commons

Pyrite

Pyrite is more commonly known as fool’s gold and is familiar to nearly every mineral collector. It has been used for centuries both in jewelry and as an ore of iron. “Marcasite” stones in jewelry are frequently pyrite, since the latter is more stable. The material is very brittle and heat sensitive and requires some care in cutting. Cabochons are sometimes cut, but they have no special appeal.

Pyrite Information

Data Value
Name Pyrite
Colors Brassy yellow, sometimes with iridescent tarnish.
Crystallography Isometric. Crystals abundant and widespread, sometimes very large and displaying an immense variety of forms; also massive, granular.
Luster Metallic.
Hardness 6-6.5
Fracture Conchoidal to uneven
Specific Gravity 5.0-5.03
Birefringence None.
Cleavage Indistinct
Stone Sizes Cabochons of any size could be cut from the large crystals that have been found. Pyrite is usually seen in inexpensive jewelry, faceted in rose—cut fashion with flat backs, similar to the older marcasite jewelry popular during the Victorian era.
Transparency Opaque.
Formula

FeS2.
Pleochroism

None.
Optics

Isotropic.

Dimorph of Marcasite.

Streak: Greenish black.

Other Tests: Nonmagnetic; insoluble in HCl.

Occurrence: The most abundant of all sulfide minerals; occurs in nearly all rock types and most geological environments. Localities too numerous to list in detail. Fine crystals are known from the following localities:

Leadville, Colorado; French Creek. Pennsylvania;

Bingham, Utah.

Elba, Italy; Ambassaguas, Spain; England; Austria;

Germany; Switzerland; Sweden; Peru; Bolivia.

Comments: Pyrite is more commonly known as fool’s gold and is familiar to nearly every mineral collector. It has been used for centuries both in jewelry and as an ore of iron. “Marcasite” stones in jewelry are frequently pyrite, since the latter is more stable. The material is very brittle and heat sensitive and requires some care in cutting. Cabochons are sometimes cut, but they have no special appeal.

Name: From the Greek word for fire, because pyrite emits sparks when struck like a flint.

by Joel E. Arem, Ph.D., FGA
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