metamorphic
Quartz Vein in Host Rock
Silicon Dioxide (SiO2) within Metasedimentary or Igneous Matrix
Hardness: 7 (quartz) vs 4-6 (matrix); Color: White milky quartz in olive-green to tan matrix; Luster: Vitreous to dull; Crystal structure: Trigonal/Hexagonal; Cleavage: None/Conchoidal.
- Hardness
- 7 (quartz) vs 4-6 (matrix)
- Color
- White milky quartz in olive-green to tan matrix
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 (quartz) vs 4-6 (matrix); Color: White milky quartz in olive-green to tan matrix; Luster: Vitreous to dull; Crystal structure: Trigonal/Hexagonal; Cleavage: None/Conchoidal.
Formation & geological history
Formed through hydrothermal processes where silica-rich hot fluids are injected into fractures of a pre-existing rock body (host rock). As the temperature and pressure drop, the quartz crystallizes within the cracks. This specimen appears to be from a metamorphic or igneous environment typical of mountain-building events.
Uses & applications
Primarily for geological study and mineral collecting. Large-scale quartz veins are major sources of high-purity silica for the glass and electronics industries and are often indicator minerals for gold prospecting.
Geological facts
Quartz is the second most abundant mineral in Earth's continental crust. Vein quartz like this is often referred to as 'bull quartz' in the mining industry and can sometimes hold tiny inclusions of precious metals.
Field identification & locations
Identify in the field by the distinct contrast between the white, glass-like quartz and the duller, darker host rock. It will easily scratch glass. Commonly found in eroded creek beds, mountain ranges, and near former tectonic plate boundaries.
