metamorphic
Tumbled greenstone (likely serpentine or nephrite)
Serpentine-group minerals, chiefly Mg₃Si₂O₅(OH)₄; possibly nephrite, a fibrous amphibole aggregate
AI-generated identification · may be incorrectOlive-green, rounded, and polished with a waxy to silky luster; hardness is typically 2.5–4 for serpentine and 6–6.5 for nephrite. The image is insufficient to determine cleavage, crystal structure, or specific gravity reliably.
Identified More metamorphic →
Explore Tumbled greenstone (likely serpentine or nephrite) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Olive-green, rounded, and polished with a waxy to silky luster; hardness is typically 2.5–4 for serpentine and 6–6.5 for nephrite. The image is insufficient to determine cleavage, crystal structure, or specific gravity reliably.
Formation & geological history
Serpentine forms when ultramafic rocks undergo hydration and metamorphism, commonly in ophiolites and fault zones; nephrite forms by metamorphic alteration of magnesium-rich rocks. A precise geological age cannot be determined visually.
Uses & applications
Used as a carving and ornamental stone, beads, cabochons, and tumbled specimens; nephrite is also a valued jade material. Serpentine is used decoratively and occasionally as a low-grade building stone.
Geological facts
The smooth triangular shape and reflective surface indicate human tumbling or polishing. A scratch test, density measurement, and magnification are needed to distinguish serpentine from jade.
Field identification & locations
Common sources include California, Oregon, Canada, New Zealand, China, and Central Asia. Serpentine is generally softer and waxier; nephrite is notably tough, denser, and resists scratching by a steel file.
More like this
