igneous and sedimentary/metamorphic mix

Quartz with Basalt inclusion

Silicon Dioxide (SiO2) with mafic silicate rock

Hardness: 7 (quartz) to 6 (basalt); Color: White/Tan (quartz) and Dark Gray/Black (basalt); Luster: Vitreous to dull; Structure: Massive; Cleavage: None

Hardness: 7 (quartz) to 6 (basalt)
Color: White/Tan (quartz) and Dark Gray/Black (basalt)
Luster: Vitreous to dull

Identified June 13, 2026More igneous and sedimentary/metamorphic mix →

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Physical properties

Hardness: 7 (quartz) to 6 (basalt); Color: White/Tan (quartz) and Dark Gray/Black (basalt); Luster: Vitreous to dull; Structure: Massive; Cleavage: None

Formation & geological history

Formed through hydrothermal processes where silica-rich fluids filled veins or fractures in existing volcanic basalt. Common in volcanic terrains across all geological ages.

Uses & applications

Primarily used as decorative stones, pocket stones for collectors, or occasionally as landscaping aggregate when found in bulk.

Geological facts

This specimen represents a contact zone between two very different geological materials. The basalt section shows vesicular texture (small holes) where gas bubbles were trapped during volcanic cooling.

Field identification & locations

Identify by the contrast between the translucent hardness of the quartz and the dark, fine-grained, porous nature of the basalt. Commonly found in riverbeds or coastal areas near volcanic activity.

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