metamorphic

Eclogite

AI-generated identification · may be incorrect

A very dense, high-pressure metamorphic rock. Primarily composed of red-to-pink almandine-pyrope garnet and green omphacite (a sodium-rich clinopyroxene). Hardness is generally 6-7, but can vary depending on weathering. High specific gravity due to its dense mineral assemblage.

Identified September 1, 2026More metamorphic →

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Physical properties

Formation & geological history

Forms deep within the Earth's mantle or in the lower crust under high-pressure, low-to-moderate temperature conditions, typically associated with the subduction of oceanic crust. Brought to the surface by tectonic processes or volcanic activity.

Uses & applications

Primarily of interest to geologists and collectors. Sometimes polished into cabochons or decorative items if the contrasting colors are striking. Historically, used to study mantle processes.

Geological facts

Eclogite is a critical rock type for understanding plate tectonics, specifically the recycling of oceanic crust into the mantle. It often contains microscopic diamonds or coesite (a high-pressure form of quartz), indicating formation at extreme depths.

Field identification & locations

Identified by its striking "Christmas tree" coloration of red/pink garnets set in a green pyroxene matrix. It's often found as nodules in kimberlite pipes or in orogenic belts where deep crust has been exhumed. Collectors look for pieces with distinct, well-preserved garnets.