metamorphic
Greenstone / altered basalt (probable)
Chlorite–actinolite–epidote rock; commonly derived from basalt or gabbro
AI-generated identification · may be incorrectFine-grained, gray-green, dull to weakly waxy luster with irregular fractures and faint foliation; typical hardness about 5–6 Mohs, though exact properties vary with mineral composition. The rounded shape appears naturally weathered or manually smoothed.
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Physical properties
Fine-grained, gray-green, dull to weakly waxy luster with irregular fractures and faint foliation; typical hardness about 5–6 Mohs, though exact properties vary with mineral composition. The rounded shape appears naturally weathered or manually smoothed.
Formation & geological history
Likely formed by low- to moderate-grade metamorphism or hydrothermal alteration of mafic volcanic rock, commonly during ancient oceanic crust formation; precise age cannot be determined visually. Common in greenstone belts, altered basalt terrains, and subduction-related rocks.
Uses & applications
Used locally as durable aggregate, landscaping stone, carving material, or a lapidary curiosity; this specimen does not appear gem quality. Greenstone artifacts and ornamental pieces can have cultural significance.
Geological facts
“Greenstone” is a field term rather than one exact mineral, and its color commonly comes from chlorite, actinolite, epidote, or serpentine.
Field identification & locations
Look for a dense green-gray body, fine grain, dark mafic streaks, and possible foliation; a knife-scratch test and streak, acid, or microscope examination would improve identification. Common worldwide, including greenstone belts in Australia, Canada, South Africa, and the United States.
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