metamorphic
Tumbled pale greenish stone, likely serpentine or altered limestone
Probable serpentine-group rock (antigorite/lizardite), possibly serpentinite; identification is visual only
AI-generated identification · may be incorrectOpaque, pale green-gray with tan mottling and a dull to waxy luster; rounded from tumbling or natural abrasion. Serpentine has Mohs hardness about 2.5–4, no obvious cleavage, and a massive/fibrous crystal structure; limestone would fizz in dilute hydrochloric acid.
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Physical properties
Opaque, pale green-gray with tan mottling and a dull to waxy luster; rounded from tumbling or natural abrasion. Serpentine has Mohs hardness about 2.5–4, no obvious cleavage, and a massive/fibrous crystal structure; limestone would fizz in dilute hydrochloric acid.
Formation & geological history
Serpentinite forms when ultramafic mantle rocks hydrothermally alter, commonly during oceanic crust formation and later tectonic uplift; many examples are Paleozoic or younger. A limestone alternative would be sedimentary calcite deposited in marine environments.
Uses & applications
Commonly sold as a decorative tumbled stone, carving material, or teaching specimen; serpentinite is also used as ornamental dimension stone, while limestone is used in cement and aggregate.
Geological facts
Serpentine’s green color comes from iron and nickel-bearing alteration minerals. Do not grind or inhale dust from unknown serpentinite because some varieties may contain asbestos-form minerals.
Field identification & locations
Look for a smooth waxy surface, green veining, low hardness, and density around 2.5–2.6; test only with proper safety equipment. Common sources include California, Italy, Canada, New Zealand, and metamorphic belts worldwide.
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