mineral

Milky quartz (rough quartz crystal)

Quartz, silicon dioxide (SiO₂)

AI-generated identification · may be incorrect

White to translucent, vitreous luster, irregular to weakly conchoidal fracture, no obvious cleavage; Mohs hardness 7 and specific gravity about 2.65. The image is somewhat blurred, so crystal faces and inclusions are uncertain.

Identified September 12, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich fluids crystallize in fractures, veins, cavities, and pegmatites, commonly in Precambrian to younger continental rocks. Quartz is abundant in southeastern Brazil, including the region near 22.9°S, 46.5°W.

Uses & applications

Used for glass, ceramics, abrasives, electronics, engineered stone, and mineral collecting; attractive transparent pieces may be used as decorative specimens or gemstones.

Geological facts

Quartz is one of Earth’s most abundant minerals and has six-sided crystals when well formed. Milky appearance results from microscopic fluid inclusions or fractures.

Field identification & locations

Likely quartz if it scratches ordinary glass and does not react with dilute acid. Distinguish calcite, which is softer (Mohs 3), has cleavage, and fizzes in acid; quartz commonly occurs in Brazilian veins and pegmatites.