Fluorapatite

specimen number:
2102479

location:
Bennett Quarry, Buckfield, Maine, USA

description:
Purple slightly translucent tabular crystals of fluorapatite measuring to 0.9 cm in size on matrix. Slight micro-damage present, still in good condition and a nice thumbnail for the species and locality.

The Bennett quarry, located in the town of Buckfield in Oxford County, Maine, is a historic open-pit gem and mineral development situated within the western Maine pegmatite field. Geologically, the locality is a highly fractionated, complex, zoned granitic pegmatite of the lithium-cesium-tantalum (LCT) family, which intruded local metamorphic rocks during the late Paleozoic Era. The quarry features a well-developed core zone that produced exceptionally well-formed crystals of morganite beryl, tourmaline, and spodumene, alongside rare accessory minerals such as hydroxylherderite and various species of phosphates. Discovered and first excavated for industrial feldspar by E. L. Bennett around 1920, the site underwent episodic commercial, developmental, and recreational operations by various mineralogists and collectors for over eighty years, including intense mechanized extraction for gem-grade specimens and mineral inventory throughout the 1970s and 1990s. While large-scale commercial gem mining has subsided, the site remains widely known for the unique species discovered in its complex core pockets.

Manganapatite is a distinct manganese-bearing variety of fluorapatite that typically forms during the late stages of pegmatite crystallization. Geologically, this variety develops when high concentrations of divalent manganese substitute directly for calcium ions within the fluorapatite crystal structure, a chemical replacement that often occurs inside highly evolved lithium-rich granitic pegmatites. The mineral usually occurs as short prismatic or tabular crystals, as well as compact massive granular blocks, displaying a unique range of colors from dark green and olive green to pale blue-green or deep indigo blue. It is heavily characterized by its response to shortwave ultraviolet radiation, under which it frequently exhibits a brilliant, characteristic mustard-yellow to bright greenish-yellow fluorescence due to the active presence of manganese ions in the calcium site of the crystal lattice.

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