Rock Identifier
Tumbled milky quartz, possibly quartzite (Quartz (SiO₂); the specimen may be a quartz-rich metamorphic rock if its texture is granular) — mineral
mineral

Tumbled milky quartz, possibly quartzite

Quartz (SiO₂); the specimen may be a quartz-rich metamorphic rock if its texture is granular

AI-generated identification · may be incorrect

White to translucent, cloudy appearance with gray-brown inclusions and a vitreous-to-waxy luster; quartz is trigonal, lacks cleavage, has Mohs hardness 7, and specific gravity about 2.65. The rounded shape indicates tumbling or natural water abrasion.

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Physical properties

White to translucent, cloudy appearance with gray-brown inclusions and a vitreous-to-waxy luster; quartz is trigonal, lacks cleavage, has Mohs hardness 7, and specific gravity about 2.65. The rounded shape indicates tumbling or natural water abrasion.

Formation & geological history

Quartz crystallizes from silica-rich igneous and hydrothermal fluids, or forms in metamorphic quartzite; the exact age and source cannot be determined from the photograph. Common host-rock formation spans much of geologic time.

Uses & applications

Used as an inexpensive lapidary, craft, and ornamental stone; quartz is also important in glass, ceramics, electronics, and industrial abrasives.

Geological facts

Milky quartz owes its cloudiness to microscopic fluid inclusions, fractures, or mineral impurities. Dark marks may be iron or manganese staining, attached matrix, or surface inclusions.

Field identification & locations

Test glass or steel cautiously: genuine quartz commonly scratches glass but not vice versa; it will not fizz in dilute acid and has no obvious cleavage. Common worldwide, including Brazil, Madagascar, the United States, and Europe.