igneous
Vesicular quartz-rich rock, possibly weathered rhyolite or hydrothermal quartz
Likely quartz (SiO₂) with altered feldspar, iron oxides, and cavities; exact identification requires testing
AI-generated identification · may be incorrectPale gray-white, earthy to glassy luster, irregular porous cavities, and possible quartz crystals. Quartz is Mohs 7 with no cleavage; the specimen’s bulk hardness and density are variable because of alteration and vugs.
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Physical properties
Pale gray-white, earthy to glassy luster, irregular porous cavities, and possible quartz crystals. Quartz is Mohs 7 with no cleavage; the specimen’s bulk hardness and density are variable because of alteration and vugs.
Formation & geological history
Likely formed from silica-rich volcanic or hydrothermal fluids, with later dissolution producing cavities and iron-oxide staining. Its precise age and setting cannot be determined from the photograph alone.
Uses & applications
Usually collected as a mineral specimen; quartz-rich material may have limited decorative use but is generally unsuitable for aggregate without testing.
Geological facts
The dark cavities may be vugs lined with quartz or other minerals, while brown coloration commonly reflects limonite or hematite. It is not possible to confirm whether it is rhyolite, altered volcanic rock, or vein quartz from appearance alone.
Field identification & locations
Look for glassy quartz that scratches glass, absence of reaction to dilute hydrochloric acid, and possible crystal linings in cavities. Commonly found in volcanic terrains and hydrothermal veins; avoid assuming a gemstone identity without hardness, streak, and mineral tests.
