mineral

Milky Quartz Pebble

Quartz (Silicon Dioxide, SiO2)

Hardness: 7 on Mohs scale; Color: Opaque white to yellowish-tan due to iron staining; Luster: Vitreous to greasy; Crystal structure: Trigonal/Hexagonal (though massive/rounded here); Cleavage: None (conchoidal fracture); Specific gravity: 2.65.

Hardness: 7 on Mohs scale
Color: Opaque white to yellowish-tan due to iron staining
Luster: Vitreous to greasy

Identified February 15, 2026More mineral →

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Physical properties

Formation & geological history

Formed from silica-rich hydrothermal veins or cooling magma. This specific specimen has been further shaped by erosion in a riverbed or coastal environment, resulting in a smooth, water-worn 'pebble' texture. Quartz is found across all geological eras.

Uses & applications

Used in glassmaking, abrasives, and as a grit in construction. Large, pure specimens are used in electronics (oscillators) and jewelry, though river pebbles like this are primarily used for decorative landscaping and decorative gravel.

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 crystal growth. Iron oxide staining (rust) often creates the yellowish patches seen on this specimen.

Field identification & locations

Identify in the field by its hardness (it can scratch glass and steel) and lack of cleavage. It is found globally in riverbeds, beaches, and soil. To collectors, it is a basic foundational specimen found in almost any rocky environment.

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