Rock Identifier
Pyrite on Quartz (Iron Sulfide (FeS2) on Silicon Dioxide (SiO2)) — mineral
mineral

Pyrite on Quartz

Iron Sulfide (FeS2) on Silicon Dioxide (SiO2)

Hardness: Pyrite (6-6.5), Quartz (7); Color: Pyrite is brassy yellow/gold, Quartz is colorless or white; Luster: Pyrite is metallic, Quartz is vitreous (glassy); Crystal Structure: Pyrite is isometric (cubic), Quartz is hexagonal (trigonal); Specific Gravity: Pyrite (approx. 5.0), Quartz (2.65).

Hardness
Pyrite (6-6
Color
Pyrite is brassy yellow/gold, Quartz is colorless or white
Luster
Pyrite is metallic, Quartz is vitreous (glassy)
Identified More mineral

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Physical properties

Hardness: Pyrite (6-6.5), Quartz (7); Color: Pyrite is brassy yellow/gold, Quartz is colorless or white; Luster: Pyrite is metallic, Quartz is vitreous (glassy); Crystal Structure: Pyrite is isometric (cubic), Quartz is hexagonal (trigonal); Specific Gravity: Pyrite (approx. 5.0), Quartz (2.65).

Formation & geological history

Formed through hydrothermal processes where hot mineral-rich fluids circulate through crustal rocks, depositing sulfide and silicate minerals in veins or cavities. Found across various geological ages, often in metamorphic or igneous environments.

Uses & applications

Pyrite is an ore of sulfur and sometimes carries gold; it is popular in crystal collecting and 'fool's gold' novelties. Quartz is used heavily in glassmaking, electronics, and various jewelry applications.

Geological facts

Commonly known as 'Fool's Gold' because its brassy color often deceived prospectors. Pyrite can actually create sparks when struck against steel. It is one of the most common sulfide minerals on Earth.

Field identification & locations

Identify in the field by the brassy color and metallic luster of the pyrite versus the hard, glassy body of the quartz. Check for a black or greenish-black streak (real gold has a yellow streak). Commonly found in the United States (Colorado, Arizona), Peru, and Spain.