mineral

Milky Quartz Pebble

Crystalline Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Milky white to translucent with yellowish iron-oxide staining; Luster: Vitreous to greasy; Crystal Structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.

Hardness: 7 on Mohs scale
Luster: Vitreous to greasy

Identified March 2, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the cooling of silica-rich hydrothermal fluids in veins or pegmatites. This specific specimen has been water-worn and smoothed by fluvial (river) or glacial transport, likely deposited during the Quaternary period.

Uses & applications

Used industrially as a source of silicon for glass, electronics, and solar panels. Heavily used in construction as aggregate. In lapidary, it is used for tumbled stones and decorative landscaping.

Geological facts

The milky appearance is caused by millions of tiny fluid inclusions (bubbles of gas or liquid) trapped during crystal growth. It is the most common mineral found in Earth's continental crust.

Field identification & locations

Identify in the field by its hardness (it will scratch glass), its lack of cleavage, and its waxy or vitreous luster. Commonly found in riverbeds, beaches, and gravel pits worldwide.

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