mineral

Milky Quartz (Water-Worn Pebble)

Silicon Dioxide (SiO2)

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

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

Identified March 7, 2026More mineral →

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Physical properties

Formation & geological history

Formed through hydrothermal processes in igneous veins or metamorphic environments. This specific specimen has been shaped into a smooth cobble by river or beach erosion over thousands of years.

Uses & applications

Used industrially as a source of silica for glass and electronics; common in landscaping, construction aggregate, and as a semi-precious stone for tumbling or jewelry.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. The 'milky' appearance is caused by tiny inclusions of gas or liquid trapped during the crystal's formation.

Field identification & locations

Identify in the field by its ability to scratch glass and its lack of cleavage. Commonly found in riverbeds, beaches, and glacial deposits worldwide. Often used by beginner collectors to practice identifying mineral hardness.

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