Rock Identifier
Milky Quartz Pebble (Quartz (Silicon Dioxide, SiO2)) — mineral
mineral

Milky Quartz Pebble

Quartz (Silicon Dioxide, SiO2)

Hardness: 7 on Mohs scale. Color: Opaque white to translucent gray with hints of yellow iron staining. Luster: Vitreous to greasy when polished. Crystal Structure: Hexagonal (trigonal). Cleavage: None (conchoidal fracture). Specific Gravity: 2.65.

Hardness
7 on Mohs scale
Luster
Vitreous to greasy when polished
Identified More mineral
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Physical properties

Hardness: 7 on Mohs scale. Color: Opaque white to translucent gray with hints of yellow iron staining. Luster: Vitreous to greasy when polished. Crystal Structure: Hexagonal (trigonal). Cleavage: None (conchoidal fracture). Specific Gravity: 2.65.

Formation & geological history

Formed from silica-rich hydrothermal solutions or as a primary constituent in igneous rocks like granite. This specific specimen has been water-worn and smoothed by alluvial or glacial transport, then likely mechanically polished.

Uses & applications

Used widely as abrasive material, in glassmaking, construction gravel, landscaping, and commonly sold as 'worry stones' or decorative vase filler.

Geological facts

Milky quartz gets its cloudy appearance from tiny microscopic inclusions of gas or liquid trapped during the crystal's growth. It is the most common variety of crystalline quartz on Earth.

Field identification & locations

Identify in the field by its hardness (it can scratch glass), lack of cleavage, and white sub-vitreous appearance. Found in almost any riverbed or beach globally where granite or quartz veins are eroded.