metamorphic
Tumbled greenstone, likely serpentine
Serpentinite/serpentine-group minerals, chiefly Mg₃Si₂O₅(OH)₄; possibly chlorite-bearing greenstone
AI-generated identification · may be incorrectGreen, opaque, mottled and weakly veined with a dull to waxy luster; typically massive rather than visibly crystalline. Serpentine has Mohs hardness about 2.5–4, poor cleavage, and specific gravity around 2.5–2.6; the polished/tumbled surface obscures diagnostic texture.
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Physical properties
Green, opaque, mottled and weakly veined with a dull to waxy luster; typically massive rather than visibly crystalline. Serpentine has Mohs hardness about 2.5–4, poor cleavage, and specific gravity around 2.5–2.6; the polished/tumbled surface obscures diagnostic texture.
Formation & geological history
Forms when magnesium-rich ultramafic rocks such as peridotite are hydrated during metamorphism, commonly in oceanic crust and subduction-related zones. Serpentinization ranges from Precambrian to modern geological settings.
Uses & applications
Used as carving stone, ornamental tile, landscaping material, and inexpensive polished specimens; some varieties are sold as “new jade,” though they are not jadeite or nephrite. Common tumbled pieces generally have modest value.
Geological facts
The specimen’s rounded shape indicates human tumbling or natural abrasion. Serpentine can resemble jade, but it is substantially softer and usually shows a more waxy, mottled appearance.
Field identification & locations
Common in California, the Appalachians, New Zealand, Italy, Canada, and oceanic ophiolites; identify with softness, waxy luster, green mottling, and lack of glassy crystal faces. Visual identification is not definitive; avoid generating dust because some serpentinite contains fibrous chrysotile.
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