mineral
Milky quartz (likely quartz crystal fragment)
Quartz, silicon dioxide (SiO₂)
AI-generated identification · may be incorrectWhite to translucent, vitreous luster, crystalline but apparently fractured or roughly shaped; Mohs hardness 7, no cleavage, conchoidal fracture, specific gravity about 2.65. The orange-brown rim may be iron-oxide staining or a metal setting rather than part of the specimen.
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Physical properties
White to translucent, vitreous luster, crystalline but apparently fractured or roughly shaped; Mohs hardness 7, no cleavage, conchoidal fracture, specific gravity about 2.65. The orange-brown rim may be iron-oxide staining or a metal setting rather than part of the specimen.
Formation & geological history
Quartz crystallizes from silica-rich hydrothermal fluids, pegmatites, and veins, commonly in Precambrian Brazilian terrains; its exact geological age cannot be determined from the photograph.
Uses & applications
Used in glass, ceramics, electronics, abrasives, and ornamental objects; attractive clear or colored pieces may be cut as gemstones, though this small cloudy fragment has modest value.
Geological facts
Quartz is one of Earth’s most abundant minerals and is strongly scratch-resistant compared with ordinary steel or glass. The image does not show diagnostic crystal faces clearly enough to confirm a rarer quartz variety.
Field identification & locations
Common around 21.0°S, 43.8°W in southeastern Brazil, where quartz-bearing veins and pegmatites occur. Test cautiously: it should scratch glass but not be scratched by a steel knife; avoid confusing it with man-made glass or white calcite, which is softer.
