metamorphic
Tumbled quartz-rich stone, likely milky quartz or quartzite
Quartz (SiO₂), possibly quartzite (recrystallized quartz sandstone)
AI-generated identification · may be incorrectWhite to gray, translucent edges, dull-to-waxy luster, granular texture, and no obvious cleavage; quartz hardness is Mohs 7, with specific gravity about 2.65. The rounded shape indicates natural abrasion or tumbling.
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Physical properties
White to gray, translucent edges, dull-to-waxy luster, granular texture, and no obvious cleavage; quartz hardness is Mohs 7, with specific gravity about 2.65. The rounded shape indicates natural abrasion or tumbling.
Formation & geological history
If quartzite, it formed when quartz sandstone was metamorphosed and recrystallized, commonly during regional mountain-building; if massive quartz, it crystallized from silica-rich hydrothermal fluids. The specimen’s exact age and formation cannot be determined from the photograph.
Uses & applications
Common quartzite is used as aggregate, road stone, landscaping material, and building stone; attractive pieces are sold as beach stones or lapidary specimens. It is generally not gem-grade.
Geological facts
The gray patches may be iron- or manganese-stained inclusions, surface weathering, or remnants of mica-rich material. Quartz does not have cleavage and commonly breaks with curved, conchoidal fractures.
Field identification & locations
Test with a steel file or knife: genuine quartz should resist scratching, while glass or calcite will scratch more easily. Common worldwide, especially in metamorphic belts, quartz veins, and gravel or beach deposits.
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