Hydroxylherderite with Cookeite
specimen number:
2102435
location:
Bennett Quarry, Buckfield, Maine, USA
description: The Bennett quarry, located in Buckfield, Oxford County, Maine, is a classic granitic pegmatite locality known for producing a diverse suite of lithium-bearing minerals and gem-quality crystals. Geologically, the deposit is a highly fractionated, zoned pegmatite body that belongs to the late Paleozoic Sebago batholith complex, intruded into older metamorphic schist host rocks. Slow cooling of volatile-rich residual magmas formed distinct inner structural zones, including core margin pockets where advanced hydrothermal alteration yielded crystallized cesian beryl, tourmaline, apatite, and rare phosphate species. Commercial quarrying at the site began around 1920, initially targeting industrial feldspar and mica, but it transitioned intermittently through the mid-to-late twentieth century into a specialized gem and mineral specimen operation. Significant mechanized mining efforts by various private leaseholders through the 1990s and into the early 2000s uncovered major mineralized pockets, and the quarry continues to be worked on a periodic, seasonal basis for specimen recovery into the twenty-first century. Hydroxylherderite is a rare calcium beryllium phosphate mineral that forms as a secondary or late-stage hydrothermal product in the complex pocket zones of evolved granitic pegmatites. The Bennett quarry is historically significant for producing exceptional specimens of this mineral, where it typically occurs as sharp monoclinic crystals, sometimes in large twins or spherical aggregat
Excellent example for the species at this locality, colorless lustrous translucent crystals to almost 1.0 cm in size with cookeite. In great condition.
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