mineral
Quartz geode or drusy quartz cluster
Quartz (silicon dioxide, SiO₂), likely a quartz-lined cavity in host rock
AI-generated identification · may be incorrectTypically hardness 7 Mohs, white to colorless, vitreous to sparkling drusy luster, and trigonal crystal structure with no cleavage. The granular cavity lining and translucent crystals are characteristic of quartz, though the specimen may include carbonate or other host minerals.
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Physical properties
Typically hardness 7 Mohs, white to colorless, vitreous to sparkling drusy luster, and trigonal crystal structure with no cleavage. The granular cavity lining and translucent crystals are characteristic of quartz, though the specimen may include carbonate or other host minerals.
Formation & geological history
Forms when silica-rich groundwater fills cavities in volcanic rock, sediment, or hydrothermal veins; quartz crystals grow inward over long periods, commonly from the Cenozoic to older geologic ages. The exact age and host rock cannot be determined from the image.
Uses & applications
Used as a decorative specimen, lapidary material, and source of collectible crystal clusters; quartz is also important in glass, electronics, abrasives, and engineered stone. This piece is primarily a display specimen.
Geological facts
The sparkling surface is drusy quartz—many tiny crystals coating a cavity. Quartz is abundant worldwide and is piezoelectric, producing an electrical charge when mechanically stressed.
Field identification & locations
Identify by its glassy sparkle, hardness, lack of cleavage, and inability to be scratched by a steel knife; it should scratch glass. Common sources include Brazil, Uruguay, Morocco, Mexico, and the United States.
