igneous
Polished orbicular granite
Granite, chiefly quartz, alkali feldspar, plagioclase, and biotite/amphibole
AI-generated identification · may be incorrectCoarse-grained, pink-white feldspar and quartz with black mafic minerals and rusty alteration; vitreous to pearly luster, interlocking crystals, no consistent cleavage as a whole, Mohs hardness about 6–7, specific gravity 2.6–2.8.
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Physical properties
Coarse-grained, pink-white feldspar and quartz with black mafic minerals and rusty alteration; vitreous to pearly luster, interlocking crystals, no consistent cleavage as a whole, Mohs hardness about 6–7, specific gravity 2.6–2.8.
Formation & geological history
A silica-rich magma crystallized slowly underground, producing a plutonic granite; the rounded orbicular texture likely reflects feldspar-rich aggregates or localized magmatic segregation. Such granites are generally Precambrian to Phanerozoic, depending on locality.
Uses & applications
Used as a decorative stone, polished sphere, countertop or architectural accent, and mineral-collecting specimen; not typically a gemstone of high intrinsic value.
Geological facts
The black material is likely biotite or hornblende, while red-brown areas may be iron-stained feldspar or hematite. Polishing emphasizes the contrasting coarse mineral mosaic.
Field identification & locations
Identify it by its visible interlocking quartz-feldspar crystals, pink coloration, black mafic minerals, and granite density; common sources include India, Brazil, Madagascar, and Scandinavia. A laboratory thin section or locality information is needed for precise naming.
