mineral

Quartz (Chert/Chalcedony variety)

Silicon Dioxide (SiO2)

Hardness: 7 (Mohs scale), Color: tan to grayish with oxidation, Luster: waxy to vitreous, Crystal Structure: Trigonal (microcrystalline), Cleavage: None (conchoidal fracture), Specific Gravity: 2.65

Identified June 25, 2026More mineral →

Identify your own rocks.

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

App Store Google Play

Physical properties

Hardness: 7 (Mohs scale), Color: tan to grayish with oxidation, Luster: waxy to vitreous, Crystal Structure: Trigonal (microcrystalline), Cleavage: None (conchoidal fracture), Specific Gravity: 2.65

Formation & geological history

Formed primarily through the accumulation of silica-rich fluids in sedimentary environments or by the precipitation of groundwater in rock cavities. These specimens are often millions of years old, found in desert or arid environments.

Uses & applications

Used historically for stone tools and arrowheads. Modern uses include aquarium gravel, decorative landscaping, and occasionally as a base material for glass-making if high in purity.

Geological facts

Quartz is the most abundant and stable mineral on Earth's surface. Varieties like chert were among the first materials used by early humans for tools due to their predictable fracturing patterns.

Field identification & locations

Identify by its inability to be scratched by a steel nail, its waxy appearance on broken edges, and its durability. Commonly found in dry washes, deserts, and gravel pits worldwide.

Other mineral specimens

See all

Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Schist

Metamorphic

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