igneous

Quartz Vein in Host Rock

Quartz (SiO2) in Mafic or Sedimentary Matrix

Hardness: 7 (quartz vein) vs 4-6 (matrix); Color: White/creamy vein in brown/grey host; Luster: Vitreous to dull; Structure: Hexagonal crystal system (microcrystalline); Cleavage: None (conchoidal fracture); SG: 2.65

Hardness: 7 (quartz vein) vs 4-6 (matrix)
Color: White/creamy vein in brown/grey host
Luster: Vitreous to dull

Identified February 21, 2026More igneous →

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Physical properties

Formation & geological history

Formed through hydrothermal deposition where mineral-rich hot fluids filled fractures in a pre-existing rock body (host rock). This typically occurs in various geological ages during tectonic activity.

Uses & applications

Used primarily as an indicator for ore deposits (like gold). Common specimens are used for landscaping, road fill, or educational geological samples.

Geological facts

Quartz veins are the most common source of 'lode gold' deposits. They represent ancient plumbing systems where fluids moved through the Earth's crust.

Field identification & locations

Identify by the sharp contrast between the white crystalline band and the darker stony matrix. Found globally in mountainous or metamorphic terrains. Test for hardness; the white vein will scratch glass.

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Basalt (extrusive igneous rock) or Diabase (intrusive igneous rock - also known as Dolerite), largely composed of plagioclase feldspar, pyroxene (augite), and sometimes olivine and amphibole. Exact mineralogy would require thin section analysis.

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Apatite (Group), Ca5(PO4)3(F,Cl,OH)

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Magnetite (Fe3O4)

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