metamorphic
Rhodonite-bearing gneiss
Manganese-rich biotite gneiss with rhodonite (MnSiO₃)
AI-generated identification · may be incorrectCoarse-grained, strongly banded rock with salmon-pink rhodonite and dark gray-black biotite/amphibole-rich layers; rhodonite hardness ~5.5–6, vitreous to pearly luster, typically triclinic. Overall specific gravity is roughly 2.8–3.4.
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Physical properties
Coarse-grained, strongly banded rock with salmon-pink rhodonite and dark gray-black biotite/amphibole-rich layers; rhodonite hardness ~5.5–6, vitreous to pearly luster, typically triclinic. Overall specific gravity is roughly 2.8–3.4.
Formation & geological history
Formed when manganese-rich sedimentary or volcanic protoliths underwent regional metamorphism, commonly during Precambrian mountain-building; the visible banding reflects mineral segregation under pressure and heat.
Uses & applications
Used as an ornamental and lapidary stone for polished slabs, carvings, and cabochons; coarse material is mainly a collector specimen rather than a construction stone.
Geological facts
The pink mineral is likely rhodonite, though pink manganese-bearing feldspar or garnet can occur in similar rocks. Black manganese oxides may form dark coatings or veins during weathering.
Field identification & locations
Identify by pink-to-red manganese silicate patches interlayered with dark foliated bands; a glassy streak and moderate hardness help distinguish it from softer rose quartz. Common occurrences include Sweden, Australia, Russia, Brazil, and the United States.
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