igneous
Weathered gray-green volcanic rock
Likely basaltic andesite or altered basalt; precise identification requires a fresh surface and testing
AI-generated identification · may be incorrectFine-grained, dull to weakly earthy luster, gray-green with rusty weathering patches; likely hardness about 5–6, dense, with no obvious cleavage and subhedral microscopic crystals. Green coloration may reflect chlorite, epidote, or other alteration minerals.
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Physical properties
Fine-grained, dull to weakly earthy luster, gray-green with rusty weathering patches; likely hardness about 5–6, dense, with no obvious cleavage and subhedral microscopic crystals. Green coloration may reflect chlorite, epidote, or other alteration minerals.
Formation & geological history
Probably an extrusive volcanic rock formed when mafic to intermediate lava cooled at or near Earth’s surface, later altered by circulating fluids and weathering. Its exact geological age and formation setting cannot be determined from the image.
Uses & applications
Commonly used as aggregate, road stone, riprap, and occasionally building stone; this weathered specimen has little jewelry value.
Geological facts
Basaltic rocks often contain plagioclase and pyroxene, while green alteration can indicate low-temperature metamorphism or hydrothermal activity.
Field identification & locations
In the field, check for a fine crystalline texture, high density, absence of visible sand grains, and a dark fresh interior; a streak, hardness, magnetism, and acid test can help distinguish it from sandstone or concrete. Common in volcanic terrains worldwide.
