metamorphic
Quartz on Greenstone
Silicon Dioxide (SiO2) on Altered Igneous Geologic Unit
Hardness: 7 (Quartz) / 5-6 (Matrix); Color: Clear/White crystals on dark green to greyish matrix; Luster: Vitreous (Quartz) to Dull (Matrix); Structure: Hexagonal crystals on massive host rock.
- Hardness
- 7 (Quartz) / 5-6 (Matrix)
- Color
- Clear/White crystals on dark green to greyish matrix
- Luster
- Vitreous (Quartz) to Dull (Matrix)
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Physical properties
Hardness: 7 (Quartz) / 5-6 (Matrix); Color: Clear/White crystals on dark green to greyish matrix; Luster: Vitreous (Quartz) to Dull (Matrix); Structure: Hexagonal crystals on massive host rock.
Formation & geological history
Formed through hydrothermal processes where silica-rich fluids circulated through cracks in low-grade metamorphic rocks (greenstone/basalt) often during orogenic (mountain-building) events.
Uses & applications
Primarily for geological study, education, or amateur rock collecting. Quartz is used industrially for electronics and abrasives, while greenstone can be used for crushed stone.
Geological facts
Greenstone belts represent some of the oldest parts of Earth's crust (Archean and Proterozoic eras). They often host significant gold deposits in the quartz veins that cut through them.
Field identification & locations
Identify by finding white, glass-like crystals that can scratch steel/glass attached to a dense, dark green, fine-grained rock. Common in the Appalachian Mountains, Canadian Shield, and Western US.
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