Biotite
specimen number:
2063518
location:
Island mine, Acworth, New Hampshire, USA
description: The Island mine, located in Cheshire County near Acworth and Alstead, New Hampshire, operates within a classic Granitic Pegmatite dike intruded into surrounding metasedimentary rock formations. Commercial extraction originally targeted high-grade industrial minerals, specifically mica and feldspar, during the nineteenth and twentieth centuries. Over time, mineral collectors recognized the locality for yielding exceptional, well-formed gemstone specimens. The site is particularly famous for producing distinct hexagonal crystals of beryl, including gem-quality light blue aquamarine and golden heliodor, alongside sub-varieties like schorl tourmaline and quartz. Today, active industrial mining has largely ceased, and the locality serves primarily as a destination for field collecting through fee-dig operations or private land access agreements.
Sharp lustrous black crystal grouping of biotite measuring 2.0 x 1.8 x 1.5 cm in size standing up free from matrix. Crystallized completely all around and in great condition. Excellent miniature for the species. The specimen comes with two previous collection labels, one from the collection of Martin Zinn and the other from the collection of Ray DeMark.
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