metamorphic
Weathered gray-green metamorphic pebble
Probable greenschist or chlorite-rich metavolcanic rock; exact identification requires testing
AI-generated identification · may be incorrectFine-grained, dull to weakly silky, gray-green material with faint foliation and rounded weathering. Likely hardness about 5–6 Mohs; cleavage is absent to weak, and specific gravity is approximately 2.7–3.0.
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Physical properties
Fine-grained, dull to weakly silky, gray-green material with faint foliation and rounded weathering. Likely hardness about 5–6 Mohs; cleavage is absent to weak, and specific gravity is approximately 2.7–3.0.
Formation & geological history
Probably formed when basaltic volcanic rock underwent low- to medium-grade regional metamorphism, producing chlorite, epidote, actinolite, albite, and quartz; age depends on locality. Its rounded shape indicates abrasion in a stream, beach, or glacial deposit.
Uses & applications
Usually used as a landscaping or teaching specimen rather than jewelry; tougher varieties can serve as aggregate or road stone. Collector value is generally minimal unless locality or texture is distinctive.
Geological facts
Greenschist-facies rocks commonly preserve original volcanic textures while developing green chlorite minerals. The specimen’s appearance alone cannot reliably distinguish greenschist from altered basalt, slate, or fine-grained schist.
Field identification & locations
Look for green-gray color, microscopic foliation, and a fine grain; a streak, hardness, acid, magnetism, and thin-section test would improve identification. Common in metamorphic belts and eroded river or coastal gravels.
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