metamorphic
Vuggy quartz-rich rock, possibly quartzite or quartz geode
Microcrystalline to crystalline SiO₂ (quartz), likely quartzite with a small quartz-lined vug
AI-generated identification · may be incorrectOff-white, massive and sugary/granular, with a small cavity containing sparkling quartz crystals; glassy to dull luster, Mohs hardness about 7, no obvious cleavage, and specific gravity near 2.65. The image alone cannot distinguish quartzite from silica-rich vein rock or a weathered geode.
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Physical properties
Off-white, massive and sugary/granular, with a small cavity containing sparkling quartz crystals; glassy to dull luster, Mohs hardness about 7, no obvious cleavage, and specific gravity near 2.65. The image alone cannot distinguish quartzite from silica-rich vein rock or a weathered geode.
Formation & geological history
Quartzite forms when quartz-rich sandstone is metamorphosed under heat and pressure; quartz veins and cavities form when silica-bearing fluids precipitate quartz in fractures. Such textures can form in rocks ranging from Precambrian to much younger ages.
Uses & applications
Typically a collector specimen; quartzite is used as aggregate, road stone, and durable building stone, while clear cavity crystals may have minor ornamental value.
Geological facts
Quartz scratches ordinary glass and steel, has conchoidal fracture, and commonly shows a white streak. The cavity is a vug rather than necessarily a true geode.
Field identification & locations
Look for abundant interlocking quartz grains, hardness near 7, and acid resistance; quartzite preserves little original bedding, whereas limestone fizzes in dilute acid. Common in metamorphic belts and quartz-vein districts worldwide.
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