Mineral

Quartz

Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 6-7 (Mohs scale), Color: Variable, often red, pink, white, gray, brown, green, black. Luster: Vitreous to greasy. Crystal Structure: Trigonal. Cleavage: None. Specific Gravity: 2.65

Color: Variable, often red, pink, white, gray, brown, green, black
Luster: Vitreous to greasy

Identified August 28, 2025More mineral →

Explore Quartz in the encyclopedia →

Identify your own rocks.

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

App Store Google Play

Physical properties

Hardness: 6-7 (Mohs scale), Color: Variable, often red, pink, white, gray, brown, green, black. Luster: Vitreous to greasy. Crystal Structure: Trigonal. Cleavage: None. Specific Gravity: 2.65

Formation & geological history

Quartz forms through the crystallization of silica (SiO2) from hydrothermal solutions, igneous melts, or during metamorphic processes. It is a primary constituent of granites and other felsic igneous rocks, and is also found in sedimentary rocks (like sandstone) and metamorphic rocks (like quartzite). Its formation can span billions of years, depending on the geological context.

Uses & applications

Quartz is widely used in many industries. It is a key component in glass manufacturing, abrasives, and as a raw material for silicon production. Due to its piezoelectric properties, it is used in electronic devices like watches, radios, and computers. Attractive varieties of quartz are extensively used as gemstones and in jewelry. In construction, it's a common aggregate in concrete and asphalt.

Geological facts

Quartz is one of the most abundant minerals in Earth's crust. It forms in a variety of temperatures and pressures, making it present in almost all rock types. Many varieties of quartz exist, distinguished by their color, structure, or impurities, such as Amethyst, Citrine, Rose Quartz, Smoky Quartz, and Chalcedony.

Field identification & locations

In the field, quartz can be identified by its glassy luster, hardness (it can scratch glass and steel), and lack of cleavage (it fractures conchoidally). It is ubiquitous and can be found globally in various geological settings, including igneous, metamorphic, and sedimentary terrains. For collectors, looking for well-formed crystals in vugs or veins, or colorful varieties in weathered rock, can be rewarding. Its resistance to weathering means it is often found as pebbles and sand in rivers and beaches.

Other mineral specimens

See all

Mineral Sand (Heavy Mineral Sand Concentrate)

Placer deposit concentrate containing minerals such as ilmenite, rutile, zircon, and magnetite

mineral

Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Calcite–fluorite mineral specimen with iron-oxide staining

Calcite (CaCO₃), likely fluorite (CaF₂), with possible quartz and iron/manganese oxides

mineral

Soil with Mineral Detritus and Quartz Fragments

Regolith / Silicate Mineral Aggregate

sedimentary

Septarian Pebble

Septarian nodule / Concretion

sedimentary

Limonite / Goethite (Iron Ore Mineral nodule)

FeO(OH)·nH2O / FeO(OH)

mineral