metamorphic
Weathered schist
Mica schist, likely chlorite–biotite schist
AI-generated identification · may be incorrectTypically gray-brown to greenish, with a sparkly micaceous luster and strong foliation; mica gives it a flaky texture and perfect cleavage along layers. Hardness is roughly 2–4 for mica-rich surfaces, while quartz grains reach 7; specific gravity is about 2.7–3.0.
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Physical properties
Typically gray-brown to greenish, with a sparkly micaceous luster and strong foliation; mica gives it a flaky texture and perfect cleavage along layers. Hardness is roughly 2–4 for mica-rich surfaces, while quartz grains reach 7; specific gravity is about 2.7–3.0.
Formation & geological history
Formed when shale or other clay-rich sediment was subjected to elevated pressure and temperature during regional metamorphism, commonly during mountain building. Its exact geological age cannot be determined from the photograph.
Uses & applications
Used locally as landscaping stone, wall stone, fill, and occasionally decorative slabs; strongly foliated pieces are generally unsuitable for high-load construction. Attractive specimens may have modest collector value.
Geological facts
The visible layered fabric is schistosity, produced by recrystallized and aligned mica minerals. Brown rusty areas likely represent oxidation of iron-bearing minerals such as biotite or sulfides.
Field identification & locations
Identify it by its thin, breakable layers, glittering mica flakes, and uneven foliation; a streak test and hand lens can help distinguish it from slate or gneiss. Common in ancient metamorphic belts worldwide, including New England, the Appalachians, Scandinavia, and the Himalayas.
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