Formula: Mn2+Mn2+2(PO4)2
Anhydrous normal phosphate, graftonite group, forms a series with graftonite
Specific gravity: 3.60 to 3.70
Hardness: 5
Streak: Light pink
Colour: Reddish-Brown to pinkish brown


Beusite is a late-stage accessory mineral in complex granite pegmatites, and it has also been found as euhedral inclusions in troilite nodules in an iron meteorite (Webmin, HOM). The beusite-graftonite series, is restricted on Earth to pegmatites where beusite is intergrown with other phosphates including triphylite and lithiophilite. It represents a breakdown of a high-temperature phase (AM 76.1985-1989).
Associated minerals include lithiophilite or triphylite in pegmatites and troilite and sarcopside in the iron meteorite (HOM).


Beusite is found in granite pegmatites in three localities in San Luis Province, Argentina: Los Aleros, Amanda and San Salvador. Many of the pegmatites of the Sierra de San Luis contain lithium and beryllium minerals. All of them at which beusite or graftonite were found have commercial amounts of spodumene, beryl or muscovite. Lithiophilite interlaminated with beusite was found in all the San Luis localities (AM 53.1799-1814).

At the type locality, the Los Aleros pegmatite, Coronel Pringles Department, San Luis Province, Argentina, beusite occurs in a granite pegmatite associated with triphylite and interlaminated with lithiophilite (Mindat).

At the Emmons pegmatite, Greenwood, Oxford county, Maine, USA, beusite occurs rarely in the margin of lithiophilite masses. The Emmons pegmatite is an example of a highly evolved boron-lithium-cesium-tantalum enriched pegmatite (R&M 94.6.505).

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