metamorphic

Tumbled garnet-bearing metamorphic rock

Likely garnet schist or garnet-bearing gneiss; garnet is commonly almandine, Fe₃Al₂(SiO₄)₃

AI-generated identification · may be incorrect

Rounded, polished specimen with dark red-purple granular areas and gray-brown matrix; likely Mohs 6.5–7.5 for garnet, vitreous to dull luster, no obvious cleavage, and moderate-to-high specific gravity (~3.5–4.3).

Identified September 19, 2026More metamorphic →

Explore Tumbled garnet-bearing metamorphic rock in the encyclopedia →

Identify your own rocks.

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

App Store Google Play

Physical properties

Formation & geological history

Formed when clay-rich sedimentary rocks underwent regional metamorphism, growing garnet crystals during burial and heating, commonly hundreds of millions to billions of years ago. The rounded shape is human-tumbled or naturally worn.

Uses & applications

Used as an abrasive and as an ornamental or lapidary stone; attractive garnet-rich pieces are collected, though this specimen appears primarily decorative rather than gem-grade.

Geological facts

Garnet crystals are often resistant to weathering and may remain as rounded grains after the surrounding rock breaks down. The red color commonly reflects iron-rich almandine garnet.

Field identification & locations

Identify it by testing for abundant hard red garnet grains in a foliated gray matrix; garnet should resist a steel knife, while the matrix may scratch more easily. Common sources include metamorphic belts in India, Madagascar, Sri Lanka, the United States, and Scandinavia.