mineral
Milky quartz (rough quartz fragment)
Quartz, silicon dioxide (SiO₂)
AI-generated identification · may be incorrectTypically hardness 7 Mohs, translucent white to gray, with a glassy luster and conchoidal fracture; it lacks cleavage and has a trigonal crystal structure. The specimen appears irregular and slightly frosted, consistent with rough milky quartz, though image-only identification is approximate.
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Physical properties
Typically hardness 7 Mohs, translucent white to gray, with a glassy luster and conchoidal fracture; it lacks cleavage and has a trigonal crystal structure. The specimen appears irregular and slightly frosted, consistent with rough milky quartz, though image-only identification is approximate.
Formation & geological history
Forms when silica-rich fluids crystallize in fractures and cavities, commonly in hydrothermal veins and igneous or metamorphic rocks. Quartz is widespread and occurs from ancient Precambrian terrains to modern geological settings.
Uses & applications
Used for glass, ceramics, engineered stone, abrasives, electronics, and occasionally inexpensive cabochons or display specimens. This rough fragment has mainly modest educational or collecting value.
Geological facts
Quartz is one of Earth’s most abundant minerals and is the defining component of many quartz veins. Its hardness allows it to scratch ordinary glass and steel, but it can be distinguished from glass by its natural fracture and lack of bubbles.
Field identification & locations
Common in quartz veins, granite, pegmatite, metamorphic rocks, and stream gravels worldwide, including Brazil, the United States, Madagascar, and the Alps. Confirm with a glass-scratch test, lack of cleavage, and absence of obvious bubbles; avoid damaging valuable specimens.
