mineral

Amethyst Geode

Silicon Dioxide (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 on Mohs scale; Color: Pale violet to deep purple; Luster: Vitreous/Glassy; Crystal structure: Trigonal (Hexagonal prisms); Cleavage: None (Conchoidal fracture); Specific gravity: 2.65

Hardness: 7 on Mohs scale
Color: Pale violet to deep purple
Luster: Vitreous/Glassy

Identified July 10, 2026More mineral →

Explore Amethyst Geode in the encyclopedia →

Identify your own rocks.

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

App Store Google Play

Physical properties

Hardness: 7 on Mohs scale; Color: Pale violet to deep purple; Luster: Vitreous/Glassy; Crystal structure: Trigonal (Hexagonal prisms); Cleavage: None (Conchoidal fracture); Specific gravity: 2.65

Formation & geological history

Formed in volcanic geodes or cavities when hot, silica-rich fluids deposit crystals over time. Most commercial specimens are from the Cretaceous period, roughly 130 million years ago, found in basaltic lava flows.

Uses & applications

Widely used in jewelry (faceting), home decor, metaphysical practices, and as a popular mineral for collectors.

Geological facts

The purple color comes from irradiation of iron impurities within the quartz lattice. Until the 18th century, amethyst was considered one of the 'Cardinal gems,' as valuable as diamond or ruby, until large deposits were found in Brazil.

Field identification & locations

Identify by its characteristic purple color and hexagonal crystal habits. Often found in South America (Brazil, Uruguay) and Africa. Collectors should look for deep purple saturation and lack of visible matrix for higher value.