igneous
Pale blue-green altered volcanic rock, likely basalt
Altered basalt (fine-grained plagioclase–pyroxene rock with secondary zeolite/chlorite minerals)
AI-generated identification · may be incorrectHardness roughly 5–6; mottled pale blue-green and white, dull to slightly waxy luster, very fine-grained and massive, with no obvious cleavage or crystal faces. The rounded edges suggest natural weathering or tumbling.
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Physical properties
Hardness roughly 5–6; mottled pale blue-green and white, dull to slightly waxy luster, very fine-grained and massive, with no obvious cleavage or crystal faces. The rounded edges suggest natural weathering or tumbling.
Formation & geological history
Likely a weathered or hydrothermally altered basaltic fragment. Basalt forms from rapidly cooled lava, commonly in volcanic provinces; alteration can produce pale green-blue chlorite, calcite, or zeolites. The image cannot establish a geological age.
Uses & applications
Usually a common field specimen or aggregate; altered basalt may be used locally for roadstone and construction. It has little jewelry value unless it contains attractive zeolite or agate cavities.
Geological facts
The blue-green color is more consistent with alteration minerals than with fresh basalt. At approximately 13.2°N, 39.2°E, volcanic rocks are geologically plausible because the region lies within the Ethiopian Rift volcanic province.
Field identification & locations
Look for a dense, fine-grained texture, irregular fracture, and absence of glassy surfaces. A steel nail may scratch it only weakly; dilute acid can reveal calcite-bearing areas, while a hand lens may show tiny white zeolite or feldspar crystals. A definitive ID requires a fresh surface, hardness, streak, and possibly thin-section or XRD testing.
