Biotite Crystal Prospect
Topsham, Sagadahoc County, Maine, USA
Key Information
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The Biotite Crystal Prospect is in Topsham, Maine, USA, a coastal New England town, now under housing, likely discontinued for mining.
It produced rare almandine garnets and biotite, with pegmatite rocks forming these minerals under heat and pressure.
Mining started in the 20th century, small-scale, discovered by enthusiasts, with nearby Porcupine Hill Quarry still active.
Topsham has a strong conservation culture, with a humid continental climate, though ecology ties to minerals are unclear.
Geographic Location
Tucked away in Topsham, Sagadahoc County, Maine, the Biotite Crystal Prospect sits in the northeastern USA, part of New England’s rugged coastline. It’s about 43° North, 69° West, a short drive from the Atlantic, with nearby famous localities like Porcupine Hill Quarry offering similar mineral treasures.
Minerals Produced
This prospect was a gem for enthusiasts, yielding razor-sharp almandine garnets and dark, flaky biotite, alongside quartz, fluorapatite, and uranium minerals like autunite. These uncommon finds, especially the garnets, made it a hotspot for collectors seeking unique specimens.
Geological Structure and Mining History
The area’s pegmatites, coarse-grained igneous rocks, birthed these minerals through intense heat and pressure, a geological saga of fire and time. Mining likely began in the 20th century, a small-scale prospecting effort by passionate collectors like Cliff Trebilcock, but it’s now history, buried under homes, with no recent activity reported.
Local Culture and Climate
Topsham thrives on conservation, with land trusts connecting people to nature, reflecting a deep environmental ethos. Its humid continental climate, with warm summers and cold winters, shapes the landscape where minerals once gleamed, though exact ecological ties remain a mystery.