metamorphic

Garnet–biotite schist (likely garnetiferous mica schist)

Garnet-bearing mica schist; chiefly quartz, biotite/muscovite, feldspar, and almandine-pyrope garnet

AI-generated identification · may be incorrect

Dark gray to brown, strongly foliated and sparkly, with aligned mica flakes and possible small reddish garnets. Mica gives a pronounced schistosity; hardness is variable, about 2–3 for mica and 6–7 for quartz, with garnet around 6.5–7.5; generally low to moderate luster and no consistent cleavage as a whole.

Identified September 2, 2026More metamorphic →

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At a glance

Common name: Garnet–biotite schist (likely garnetiferous mica schist)
Scientific name: Garnet-bearing mica schist; chiefly quartz, biotite/muscovite, feldspar, and almandine-pyrope garnet
Category: metamorphic
Identified: September 2, 2026
Method: Standard

AI Estimated Value

About $5–$25 for a common hand specimen; $30–$100 if garnet-rich, attractive, or professionally prepared.

Not an official valuation

AI estimate for general interest only — not an appraisal. Actual value depends on condition, provenance, and market demand. Verify with a professional before buying, selling, or insuring.

This identification was generated by AI and may contain errors. Verify important details before relying on them — and never use an AI result to judge whether a specimen is safe to handle. Read the full disclaimer

Physical properties

Formation & geological history

Formed when clay-rich sedimentary rock was buried, heated, and compressed during regional metamorphism, commonly during Precambrian–Paleozoic mountain building. The reported southeastern Democratic Republic of Congo location is geologically plausible for ancient metamorphic basement rocks.

Uses & applications

Used locally as dimension stone, aggregate, or decorative stone, but strong foliation limits construction durability. Attractive pieces may be collected, though this specimen appears ordinary and unpolished.

Geological facts

Schistosity develops as platy mica minerals recrystallize and align under directed pressure. Weathering commonly produces rusty brown patches from iron-bearing biotite or garnet.

Field identification & locations

Identify it by splitting along shiny, wavy mica-rich layers and testing visible grains: quartz is hard and glassy, while mica flakes peel easily. Confirm garnet by looking for equant reddish-brown grains; a fresh surface and hand lens would improve certainty.