igneous
Polished dark green igneous pebble
Likely gabbro or diabase (dolerite), composed mainly of plagioclase feldspar and pyroxene
AI-generated identification · may be incorrectFine- to medium-grained, dark green-black, with a mottled granular texture and dull to subtly vitreous luster; hardness about 6–7 Mohs, massive structure, no obvious cleavage on the surface, and specific gravity roughly 2.8–3.1.
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Physical properties
Fine- to medium-grained, dark green-black, with a mottled granular texture and dull to subtly vitreous luster; hardness about 6–7 Mohs, massive structure, no obvious cleavage on the surface, and specific gravity roughly 2.8–3.1.
Formation & geological history
Formed when basaltic magma crystallized slowly underground, producing coarse gabbro, or in shallow dikes as diabase. Such rocks commonly range from Precambrian to Mesozoic in age, depending on locality.
Uses & applications
Used as durable aggregate, roadstone, landscaping stone, monuments, and polished decorative specimens; generally not suitable as a gemstone except for ornamental use.
Geological facts
The green coloration commonly reflects altered pyroxene or amphibole minerals. Its dense, interlocking grains make it resistant to weathering and scratching.
Field identification & locations
Identify it by its heavy weight, dark granular appearance, lack of vesicles, and inability to fizz with dilute hydrochloric acid; a streak test is usually pale gray. Common in ancient continental shields, oceanic crust, and mafic dike provinces.
