mineral

Quartz vein in dark host rock

Microcrystalline to crystalline quartz (SiO₂), likely in basalt or another mafic host

AI-generated identification · may be incorrect

White to translucent quartz with glassy-to-dull luster, irregular fracture, and rusty-brown iron-oxide staining or limonite cavities; Mohs hardness 7. The dark portion is fine-grained and may be basalt, though exact identification requires testing.

Identified August 25, 2026More mineral →

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Physical properties

Formation & geological history

Likely formed when silica-rich hydrothermal fluids filled a fracture in older volcanic rock, with later oxidation producing the brown staining. Its age depends on the host formation and cannot be determined from the image.

Uses & applications

Quartz specimens are collected and used in glass, electronics, abrasives, and engineered stone; basalt is widely used as aggregate and construction stone. This small piece has modest decorative and educational value.

Geological facts

The sharp boundary records an ancient healed fracture or vein. Brown coatings commonly represent hydrated iron oxides such as limonite rather than a primary quartz color.

Field identification & locations

Look for quartz’s ability to scratch glass and lack of cleavage; basalt is typically dark, fine-grained, and heavier. Common settings include volcanic terrains and hydrothermal vein systems.