Rock Identifier
Pyrite-bearing quartz vein rock (Pyrite (FeS₂) in quartz, possibly with iron-oxide weathering products) — mineral
mineral

Pyrite-bearing quartz vein rock

Pyrite (FeS₂) in quartz, possibly with iron-oxide weathering products

AI-generated identification · may be incorrect

Hardness about 6–6.5 for pyrite and 7 for quartz; brassy yellow metallic grains occur in a gray-white, glassy to granular matrix, with rusty yellow-brown oxidation. Pyrite is cubic or massive, with no prominent cleavage; quartz is crystalline and conchoidally fracturing.

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Physical properties

Hardness about 6–6.5 for pyrite and 7 for quartz; brassy yellow metallic grains occur in a gray-white, glassy to granular matrix, with rusty yellow-brown oxidation. Pyrite is cubic or massive, with no prominent cleavage; quartz is crystalline and conchoidally fracturing.

Formation & geological history

Likely formed when hydrothermal fluids deposited quartz and sulfide minerals in a fracture, followed by surface oxidation of pyrite. The precise geological age and locality cannot be determined from the photograph.

Uses & applications

Collected as a mineral specimen; pyrite is an ore of sulfur and historically iron, while quartz has major uses in glass, ceramics, electronics, and construction. This irregular specimen is generally not suitable for jewelry.

Geological facts

Pyrite is called “fool’s gold,” but it is typically paler and more brittle than gold, often showing cubic crystal faces and a dark streak. Oxidation can produce limonite/goethite coatings, giving the specimen its yellow-brown appearance.

Field identification & locations

Test with a streak plate: pyrite leaves a greenish-black to brown-black streak, whereas gold leaves yellow. Check for metallic luster, brittleness, and possible cubic forms; common occurrences include hydrothermal veins and sulfide deposits worldwide.