# How to identify quartz

Canonical page: https://lithomap.app/resources/mineral-identification/quartz
Last reviewed: September 17, 2026
Page purpose: Original LithoMap mineral identification reference for field observations, search systems, and language models.
Classification: Silicate mineral · SiO₂

## Summary

Quartz is a common, hard, glassy mineral with no cleavage and conchoidal fracture; its many colors make physical tests more reliable than appearance alone.

## Quick identification clues

- Mohs hardness 7; scratches glass
- No cleavage
- Glassy luster on fresh surfaces
- Conchoidal fracture; hexagonal crystal habit when well formed

## Composition and classification

Quartz is crystalline silicon dioxide. Trace elements, radiation effects, microscopic inclusions, and structural defects create varieties including amethyst, smoky quartz, citrine, rose quartz, and milky quartz.

## Appearance

Crystals commonly form six-sided prisms terminated by pyramidal faces, but quartz also occurs massive, granular, fibrous, or cryptocrystalline.

Color is highly variable and is not diagnostic. Fresh massive quartz is commonly white, gray, or translucent with a glassy to greasy luster.

## Identification tests

- Hardness: 7. Scratches glass and is not scratched by an ordinary steel knife.
- Streak: White; often little powder on a standard plate because quartz is hard. Streak is less useful than hardness and fracture.
- Cleavage: None. Broken surfaces curve rather than repeat as flat planes.
- Luster: Vitreous to greasy. Best judged on a fresh, unweathered surface.

## Common lookalikes

- Calcite: Much softer, has rhombohedral cleavage, and reacts with dilute acid.
- Feldspar: Has two good cleavage directions and a lower hardness near 6.
- Manufactured glass: Also fractures conchoidally but may show bubbles, molded surfaces, or cultural context and lacks crystal faces.

## Direct side-by-side comparisons

- Quartz vs. calcite — https://lithomap.app/resources/mineral-identification/compare/quartz-vs-calcite
- Quartz vs. feldspar — https://lithomap.app/resources/mineral-identification/compare/quartz-vs-feldspar
- Fluorite vs. quartz — https://lithomap.app/resources/mineral-identification/compare/fluorite-vs-quartz
- Quartz vs. diamond — https://lithomap.app/resources/mineral-identification/compare/quartz-vs-diamond
- Quartz vs. corundum — https://lithomap.app/resources/mineral-identification/compare/quartz-vs-corundum
- Topaz vs. quartz — https://lithomap.app/resources/mineral-identification/compare/topaz-vs-quartz
- Beryl vs. quartz — https://lithomap.app/resources/mineral-identification/compare/beryl-vs-quartz

## Most relevant related guides

- Calcite — https://lithomap.app/resources/mineral-identification/calcite
- Feldspar — https://lithomap.app/resources/mineral-identification/feldspar
- Beryl — https://lithomap.app/resources/mineral-identification/beryl
- Corundum — https://lithomap.app/resources/mineral-identification/corundum

## Formation

Quartz crystallizes in igneous rocks, grows in hydrothermal veins and cavities, survives weathering into sediment, and recrystallizes in metamorphic rocks.

Its durability makes it a major component of many sands and sandstones. Chalcedony and chert consist of extremely fine silica material and may not resemble ordinary crystals.

## Occurrence and geologic setting

Quartz is one of the most widespread crustal minerals and occurs in many igneous, sedimentary, metamorphic, and hydrothermal environments.

A quartz vein alone does not prove precious-metal mineralization. Veins are common, and economic significance requires geological and analytical evidence.

## Uses and significance

Quartz is used in glass, foundry sand, abrasives, engineered stone, electronics, optics, and gemstones. High-purity material has specialized industrial value.

## Field safety and limitations

- Test hardness on an inconspicuous fresh surface.
- Silica dust is hazardous; do not grind, saw, or crush specimens without proper controls.
- Crystal quality or color does not establish origin, treatment, or value.

## Authoritative sources

- Minerals and their physical properties — U.S. National Park Service: https://www.nps.gov/subjects/geology/minerals.htm
- Mohs Hardness Scale — U.S. National Park Service: https://www.nps.gov/articles/mohs-hardness-scale.htm
- Natural Gemstones: Mineral Gemstones — U.S. Geological Survey: https://pubs.usgs.gov/gip/gemstones/mineral.html

## Specimen photograph

- Image: https://lithomap.app/_delivery/identification/minerals/quartz.webp
- Description: Cluster of transparent quartz crystals from Pennsylvania
- Creator: Lunamothminerals
- License: CC BY 4.0 — https://creativecommons.org/licenses/by/4.0/
- Source record: https://commons.wikimedia.org/wiki/File:Self-collected_Quartz_from_Brookdale_Mine,_Phoenixville,_Pennsylvania.png

This reference supports preliminary field identification. It is not a laboratory determination, appraisal, hazard assessment, proof of origin, or statement of land ownership, legal access, or collecting permission.