metamorphic
Likely serpentinite (serpentine-rich rock)
Serpentine-group minerals, chiefly antigorite/lizardite; commonly derived from ultramafic peridotite
AI-generated identification · may be incorrectGreen, mottled, fine-grained, and dull to waxy with possible fibrous texture; hardness about 2.5–4 Mohs, usually massive with no obvious cleavage. The image is insufficient for reliable identification or mineral testing.
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Physical properties
Green, mottled, fine-grained, and dull to waxy with possible fibrous texture; hardness about 2.5–4 Mohs, usually massive with no obvious cleavage. The image is insufficient for reliable identification or mineral testing.
Formation & geological history
Forms when water alters mantle-derived peridotite, commonly along faults and ancient oceanic crust. Serpentinite occurrences are possible in the broader Lake Superior region, though exact local geology is needed; age may range from Precambrian to younger tectonic events.
Uses & applications
Used as an ornamental and carving stone, aggregate, and historically as a source of asbestos-bearing minerals. Avoid cutting, drilling, or sanding until asbestos content is excluded.
Geological facts
Green coloration may also result from chlorite, epidote, or altered volcanic rock, so this is a visual estimate rather than a confirmed diagnosis.
Field identification & locations
Test fresh surfaces for a waxy feel and low hardness; serpentine may scratch with a steel nail but not glass. A streak, acid test, hardness test, and thin-section or XRD analysis would improve confidence. Common regional alternatives include greenstone, chlorite schist, and altered basalt.
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