mineral

Milky Quartz Pebble

Quartz (SiO2)

Hardness: 7 on Mohs scale; Color: Milky white with brownish iron oxide staining; Luster: Vitreous to greasy; Crystal Structure: Trigonal (microcrystalline/massive aggregate in pebble form); Cleavage: None (fractures shell-like/conchoidal); Specific Gravity: 2.65

Hardness: 7 on Mohs scale
Color: Milky white with brownish iron oxide staining
Luster: Vitreous to greasy

Identified July 26, 2026More mineral →

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Physical properties

Formation & geological history

Formed in hydrothermal veins and pegmatites where silica-rich fluids cooled and crystallized. Fluid inclusions (trapped microscopic water droplets) give it the cloudy white appearance. The smooth, rounded pebble shape indicates significant erosion and transport by river or stream water.

Uses & applications

Used primarily for decorative landscaping, aquariums, lapidary tumbling, and aggregate. Pure quartz is also crushed and melted for glass manufacture and silicon production.

Geological facts

Milky quartz gets its characteristic opaque white color from millions of tiny gas or liquid bubbles trapped inside the crystal during its formation millions of years ago.

Field identification & locations

Easily identified by its hardness (scratches glass and steel), lack of cleavage, smooth water-worn surface, and milky-white color with brownish weathering seams. Very common in riverbeds, gravel pits, and beaches worldwide.