metamorphic
Grey-green granitic gneiss (possibly granitoid basement rock)
Felsic orthogneiss; mainly quartz, K-feldspar/plagioclase, and biotite/amphibole
AI-generated identification · may be incorrectFine- to medium-grained, grey-green, speckled texture with weak compositional banding and dull to slightly vitreous luster. Typical hardness ~6–7 Mohs; no obvious cleavage as a whole rock; density ~2.6–2.8 g/cm³.
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Physical properties
Fine- to medium-grained, grey-green, speckled texture with weak compositional banding and dull to slightly vitreous luster. Typical hardness ~6–7 Mohs; no obvious cleavage as a whole rock; density ~2.6–2.8 g/cm³.
Formation & geological history
Metamorphosed ancient felsic intrusive rock under high temperature and pressure, producing recrystallization and possible gneissic fabric. Botswana basement includes Archean to Proterozoic terranes, commonly hundreds of millions to over 2.5 billion years old.
Uses & applications
Crushed aggregate, roadstone, dimension stone, and geological core analysis; attractive polished pieces may be used decoratively, but it is generally not a gemstone.
Geological facts
The green tint may reflect epidote, chlorite, or hornblende rather than a distinct green mineral species. The image appears to show a diamond-drill core, not a loose hand specimen.
Field identification & locations
Identify by interlocking quartz–feldspar grains, dark mica/amphibole flecks, and faint banding; a streak test is usually white to pale grey. Around 20.2°S, 24.6°E, granitoid/gneissic basement is regionally plausible, though exact identification requires thin-section or XRF data.
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