metamorphic
Serpentinite (Polished Egg)
Serpentinite (composed mainly of serpentine group minerals, Mg3Si2O5(OH)4)
AI-generated identification · may be incorrectHardness 2.5 - 4 on Mohs scale; dark mottled green, grey, and black with subtle veining and patches; waxy to dull or vitreous luster when polished; dense, compact structure with fibrous/foliated texture; specific gravity ~2.5 - 2.8.
Identified More metamorphic →
Explore Serpentinite (Polished Egg) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness 2.5 - 4 on Mohs scale; dark mottled green, grey, and black with subtle veining and patches; waxy to dull or vitreous luster when polished; dense, compact structure with fibrous/foliated texture; specific gravity ~2.5 - 2.8.
Formation & geological history
Formed through hydrothermal metamorphism and hydration of ultramafic rocks (like peridotite and dunite) from the Earth's mantle, typical of ocean-floor spreading zones and subduction-related ophiolite sequences.
Uses & applications
Commonly carved and polished into ornamental decorative objects, cabochons, beads, architectural facing stones, and counter surfaces. Historically used for carving due to moderate softness.
Geological facts
Serpentinite gets its name from its mottled green appearance that resembles snakeskin. It is the official state rock of California and often hosts asbestos-group minerals within unpolished natural veins.
Field identification & locations
Identified by its mottled olive to dark green coloration, slightly soapy or greasy feel, moderate softness (often scratchable with a copper coin or steel nail), and greasy-to-waxy luster. Found widely along convergent plate boundaries, including the US West Coast, Italy, Greece, and New Zealand.
More like this
