mineral

Rough Quartz (Milky Quartz Pebbles)

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Milky white to tan/yellowish (due to iron staining or impurities); Luster: Vitreous to waxy; Crystal structure: Trigonal/Hexagonal (though usually massive/anhedral in pebbles); Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Hardness: 7 on Mohs scale
Luster: Vitreous to waxy

Identified March 20, 2026More mineral →

Identify your own rocks.

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

App Store Google Play

Physical properties

Formation & geological history

Formed through the cooling of silica-rich magma or precipitation from hydrothermal veins. The rounded shape indicates erosion and transport by water over significant time periods (likely Quaternary period for surface deposits).

Uses & applications

Used in glassmaking, as an abrasive, in electronics (piezoelectric properties), construction aggregate, and as landscaping gravel. Rough specimens are common for beginner mineral collecting.

Geological facts

Quartz is the second most abundant mineral in the Earth's continental crust. It is highly resistant to chemical and physical weathering, which is why it often survives as rounded pebbles and sand grains long after other minerals have decomposed.

Field identification & locations

Identify in the field by its inability to be scratched by a steel knife (hardness test) and its lack of cleavage. Often found in riverbeds, glacial tills, and along beaches globally.

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