igneous
Gold Ore in Quartz
Auriferous Quartz (Au + SiO2)
Hardness: 7 (Quartz) to 2.5-3 (Gold); Color: Milky white to tan quartz with metallic yellow inclusions; Luster: Vitreous quartz with metallic gold; Crystal Structure: Hexagonal (Quartz) / Cubic (Gold); Specific Gravity: ~2.65 (Quartz) to 19.3 (Pure Gold).
- Hardness
- 7 (Quartz) to 2
- Color
- Milky white to tan quartz with metallic yellow inclusions
- Luster
- Vitreous quartz with metallic gold
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Physical properties
Hardness: 7 (Quartz) to 2.5-3 (Gold); Color: Milky white to tan quartz with metallic yellow inclusions; Luster: Vitreous quartz with metallic gold; Crystal Structure: Hexagonal (Quartz) / Cubic (Gold); Specific Gravity: ~2.65 (Quartz) to 19.3 (Pure Gold).
Formation & geological history
Formed through hydrothermal processes where hot, mineral-rich fluids circulate through crustal fractures (veins) and cool, depositing quartz and native metals. Typically associated with Orogenic gold deposits or intrusions.
Uses & applications
Primary source for industrial gold production, geological research, and highly prized as a collector's specimen or used in 'specimen gold' jewelry.
Geological facts
Most of the world's gold was originally formed in these quartz veins before being eroded into rivers as 'placer gold'. High-grade gold-in-quartz is often referred to as 'jewelry grade' due to its aesthetic contrast.
Field identification & locations
Identify in the field by looking for heavy, iron-stained quartz (gossan) with visible yellow metallic flecks that do not shatter when poked with a needle (unlike pyrite). Commonly found in historic gold-mining regions like California, Alaska, and Australia.
