metamorphic
Tumbled white quartzite or milky quartz
Quartzite; predominantly microcrystalline quartz (SiO₂), though a quartz pebble is also possible
AI-generated identification · may be incorrectHardness about 7 Mohs; white to cream with tan iron-oxide staining and gray streaks, vitreous to waxy luster, massive granular texture, and no obvious cleavage. The rounded, polished shape indicates natural water wear or tumbling.
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Physical properties
Hardness about 7 Mohs; white to cream with tan iron-oxide staining and gray streaks, vitreous to waxy luster, massive granular texture, and no obvious cleavage. The rounded, polished shape indicates natural water wear or tumbling.
Formation & geological history
Quartzite forms when quartz-rich sandstone is metamorphosed under heat and pressure, commonly during mountain-building; its exact geological age cannot be determined visually. If it is milky quartz rather than quartzite, it formed from silica-rich hydrothermal fluids in veins.
Uses & applications
Used as a decorative tumbled stone, paperweight, and lapidary material; quartzite is also used as aggregate, building stone, and countertops. This appearance has modest jewelry value.
Geological facts
Quartz is highly resistant to weathering, allowing quartz-rich pebbles to survive transport and become smoothly rounded. Tan coloration commonly comes from iron oxides in fractures or pores.
Field identification & locations
Confirm with a scratch test: it should scratch ordinary glass, while steel should not scratch it; quartzite usually shows a granular texture, whereas quartz may appear more uniformly translucent. Common worldwide in quartz-rich river gravels and metamorphic terrains.
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