mineral

Milky Quartz Pebble

Quartz (Silicon Dioxide, SiO2)

Hardness: 7 on Mohs scale; Color: Opaque white with iron staining (yellowish-brown); Luster: Vitreous to greasy; Crystal Structure: Trigonal; Cleavage: None/Conchoidal fracture; Specific Gravity: 2.65.

Hardness: 7 on Mohs scale
Color: Opaque white with iron staining (yellowish-brown)
Luster: Vitreous to greasy

Identified May 15, 2026More mineral →

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Physical properties

Formation & geological history

Formed primarily in hydrothermal veins or as a constituent of igneous rocks like granite. This specific specimen is a water-worn river pebble, likely transported and smoothed by water over long geological periods.

Uses & applications

Used in construction as aggregate, in glassmaking, as an abrasive, and sometimes in landscaping. High-purity quartz is used in electronics for its piezoelectric properties.

Geological facts

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

Field identification & locations

Identified by its white color, inability to be scratched by a steel knife, and rounded 'river rock' texture. It is ubiquitous in riverbeds, glacial deposits, and mountain trails worldwide.