Identification guide · Metamorphic Rocks
How to Identify Eclogite
Eclogite is identified by its coarse, granular texture and striking two-mineral color contrast: red to reddish-brown garnet grains set within a matrix of bright green to yellow-green omphacite pyroxene. It has an overall hardness reflecting its garnet and pyroxene content, roughly 6 to 7, no rock-scale cleavage but a granular fracture, and it lacks the strong foliation typical of schist or gneiss because eclogite generally forms without abundant mica. It can be mistaken for garnet-bearing amphibolite, but amphibolite contains black hornblende rather than green pyroxene, and eclogite's omphacite has a paler, more yellow-green color than amphibole's dark green to black tone.
Eclogite identification checklist
| Color | Green (omphacite), Red (garnet), Mottled green and red | Look at a clean, dry surface in daylight. Color zoning, banding or spots are as diagnostic as the hue. |
|---|---|---|
| Luster | Vitreous (garnet and omphacite grains) | Fresh surfaces shine like glass; a dull surface usually means weathering, so chip or wet a corner. |
| Transparency | Opaque | Hold a thin edge up to a bright light and note whether light passes through. |
| Mohs hardness | 6–7.5 | It scratches glass and a steel knife and cannot be scratched by a steel file. |
| Fracture | Uneven | |
| Specific gravity | 3.3–3.6 | Heavier than it looks (specific gravity about 3.45). |
Eclogite look-alikes and how to tell them apart
Both sit near Mohs 6–7.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Eclogite vs Garnet →
Both sit near Mohs 6–7.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Eclogite vs Jasper →
Both sit near Mohs 6–7.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Eclogite vs Unakite →
Both sit near Mohs 6–7.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
Eclogite identification FAQ
How can you tell if a rock is Eclogite?
Check the color (green (omphacite), red (garnet), and mottled green and red), the vitreous (garnet and omphacite grains) luster, a Mohs hardness of 6–7.5. Photographing it with the StoneSnap app gives a match in seconds.
What is the hardness of Eclogite?
Eclogite has a Mohs hardness of 6–7.5. It scratches glass and a steel knife and cannot be scratched by a steel file.
What is the difference between Eclogite and Garnet?
Eclogite (Mohs 6–7.5, vitreous (garnet and omphacite grains) luster) and Garnet (Mohs 7, vitreous luster) look alike, but hardness, streak and heft usually separate them. See the full Eclogite vs Garnet comparison for a side-by-side table.
Is Eclogite worth anything?
Entry-level Eclogite specimens sell for around $1, typical collector pieces about $10, and premium examples $75 or more depending on size, quality and locality.
What color is Eclogite?
Eclogite is most often green (omphacite), red (garnet), and mottled green and red. Color varies with impurities and locality, so confirm with hardness and luster rather than color alone.
