mineral

Amethyst in Matrix

Amethyst (Silicon Dioxide), Formula: SiO2

Hardness: 7 (Mohs scale); Color: Purple/violet crystalline areas within reddish-brown iron-rich Matrix; Luster: Vitreous when crystalline; Crystal structure: Trigonal/Hexagonal; Cleavage: None/Conchoidal fracture; Specific gravity: 2.65

Hardness: 7 (Mohs scale)
Luster: Vitreous when crystalline

Identified June 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 in hydrothermal veins or as linings in volcanic geodes (cavities) through the cooling of silica-rich fluids. The purple color is caused by natural irradiation and trace amounts of iron within the quartz structure.

Uses & applications

Used primarily for jewelry, lapidary art, and as decorative collector specimens. Also popular in metaphysical and crystal healing communities.

Geological facts

Amethyst is the birthstone for February. It was once considered as valuable as diamonds, rubies, and emeralds before the discovery of large deposits in Brazil and Uruguay in the 19th century.

Field identification & locations

Identify in the field by looking for translucent purple crystals inside boring-looking brownish or grey rock rinds (matrix). Common locations include Brazil, Uruguay, South Korea, Russia, and the United States (Arizona/Georgia).

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