Milky quartz

Typically translucent white to gray with a vitreous luster, irregular fracture, and no cleavage; Mohs hardness 7, hexagonal crystal structure, and specific gravity about 2.65.

Forms when silica-rich fluids crystallize in veins, cavities, and igneous or metamorphic rocks. Quartz is common from Precambrian to modern geological settings; this rough fragment is consistent with massive or milky quartz.

Used for glass, ceramics, abrasives, engineered stone, and electronics; attractive pieces are sold as inexpensive mineral specimens or carved objects.

The cloudy appearance results from microscopic fluid inclusions, fractures, or trapped impurities. Quartz is one of Earth’s most abundant and chemically durable minerals.

Common worldwide, including Brazil, Madagascar, the United States, and Alpine regions. It is identified by its glassy luster, white translucency, lack of cleavage, and ability to scratch ordinary glass; the image alone cannot exclude calcite or another pale mineral.