mineral

Milky Quartz (Water-worn Pebble)

Quartz (Silicon Dioxide) - SiO2

Hardness: 7 on Mohs scale; Color: Cloudy white to grayish with dark inclusions; Luster: Vitreous to greasy; Crystal structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65.

Hardness: 7 on Mohs scale
Color: Cloudy white to grayish with dark inclusions
Luster: Vitreous to greasy

Identified March 24, 2026More mineral →

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Physical properties

Formation & geological history

Formed from silica-rich hydrothermal veins or as a primary constituent in igneous and metamorphic rocks. This specific specimen has been rounded and smoothed through fluvial or marine erosion (water-worn).

Uses & applications

Industrial use as an abrasive, in glassmaking, and electronics (due to piezoelectric properties). In this tumbled form, it is used for landscaping, aquarium gravel, and low-cost lapidary work.

Geological facts

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

Field identification & locations

Identify in the field by its ability to scratch glass, lack of cleavage, and smooth, rounded surface if found in riverbeds. It is found globally in almost all geological environments.

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