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
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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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