metamorphic
Tumbled serpentine-rich rock
Serpentinite, likely antigorite/lizardite with magnetite and minor carbonates
AI-generated identification · may be incorrectTypically green to yellow-brown, mottled or veined, with waxy to dull luster; Mohs hardness about 2.5–4, massive rather than visibly crystalline, and specific gravity roughly 2.5–2.6. The rounded shape indicates tumbling or natural abrasion.
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Physical properties
Typically green to yellow-brown, mottled or veined, with waxy to dull luster; Mohs hardness about 2.5–4, massive rather than visibly crystalline, and specific gravity roughly 2.5–2.6. The rounded shape indicates tumbling or natural abrasion.
Formation & geological history
Formed when ultramafic mantle rocks such as peridotite hydrated and altered during tectonic processes, commonly along oceanic crust and plate boundaries. Serpentinite ranges from Precambrian to modern tectonic settings; age cannot be determined from the photo.
Uses & applications
Used as ornamental stone, carving material, tumbled specimens, countertops, and historically as a jade substitute; some varieties are collected for attractive patterns. Avoid dust from cutting because asbestos-group minerals may occur in some serpentinites.
Geological facts
The dark green bands commonly reflect magnetite-rich or less-altered zones, while yellow areas may contain iron-rich serpentine or weathering products. Serpentinite can feel slightly soapy or waxy and may be unusually dense for its appearance.
Field identification & locations
Look for mottled green, yellow, and black coloration, waxy texture, low hardness, and occasional magnetic response from magnetite; exact identification requires testing or microscopy. Common sources include California, Oregon, Italy, New Zealand, and the Ural Mountains.
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