Quartz (milky variety)

Hardness: 7 (Mohs scale), Color: White to off-white, often with a translucent to opaque appearance due to microscopic fluid inclusions, Luster: Vitreous (glassy) to greasy on fractured surfaces, Crystal structure: Hexagonal (trigonal system), Cleavage: None (fractures conchoidally), Specific gravity: 2.65

Quartz is one of the most abundant minerals in the Earth's crust. Milky quartz commonly forms in hydrothermal veins, pegmatites, and granitic rocks. It crystallizes from silica-rich fluids over a wide range of temperatures and pressures. Its geological age varies widely depending on the specific deposit, ranging from Precambrian to relatively recent formations.

Milky quartz is less commonly used as a gemstone due to its opacity, but it can be cut into cabochons or beads. Industrially, quartz is crucial as a source of silicon for electronics, in glass manufacturing, as an abrasive, and in ceramics. It's also used as a flux in metallurgy and in various construction applications as aggregate.

Milky quartz gets its characteristic cloudy or milky appearance from millions of microscopic fluid inclusions, often water or carbon dioxide, trapped within the crystal structure during its growth. It is chemically identical to clear quartz, amethyst, citrine, rose quartz, and smoky quartz, with color variations arising from different trace elements or inclusions.

In the field, milky quartz can be identified by its characteristic white to off-white, often dull, translucent to opaque appearance, hardness (it will scratch glass or steel), and absence of cleavage, resulting in a conchoidal fracture. It is found globally in almost every geological environment, often as large veins or masses. Collectors appreciate large specimens or those with interesting mineral associations. It can be differentiated from feldspar by its lack of cleavage and often more vitreous luster.