mineral

Quartz (Milky/Opaque variety)

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Opaque white; Luster: Vitreous to waxy; Crystal structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Hardness: 7 on Mohs scale
Color: Opaque white
Luster: Vitreous to waxy

Identified March 21, 2026More mineral →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Hardness: 7 on Mohs scale; Color: Opaque white; Luster: Vitreous to waxy; Crystal structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Formation & geological history

Formed from the cooling of silica-rich magma or through hydrothermal activity in veins. Milky quartz specifically contains microscopic fluid inclusions of gas or liquid trapped during crystal growth. Found in many geological ages from Precambrian to recent.

Uses & applications

Used in glass manufacturing, as an abrasive, in the production of silicon chips, and as decorative gravel or landscaping stone. Higher quality quartz is used in jewelry and timekeeping.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. Pure quartz is clear; the white 'milky' color is caused by millions of tiny bubbles trapped inside.

Field identification & locations

Identify in the field by its hardness (will scratch glass and common pocket knives), lack of cleavage, and white opaque color. It is commonly found in gravel beds, mountain ranges, and near volcanic sites worldwide.

Other mineral specimens

See all

Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

metamorphic

Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock

Green Apatite on Albite

Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]

mineral

Epidote

Epidote - Ca2(Al2,Fe3+)3(SiO4)3(OH)

mineral