Formula: Ca3Al7.7Si3P4O23.5(OH)14.1.8H2O
Compound phosphate
Specific gravity: 2.64
Hardness: 5
Streak: White
Colour: Colourless, white, light brown, orange
Common impurities: Ti,Fe,Mg,Na,F



At the phosphate deposits of South Australia, perhamite is most often found as pseudomorphs after other phosphate minerals, such as fluellite, minyulite and especially wavellite (AJM 17.1.24).

At the Moculta phosphate quarry, Angaston, Barossa Valley, Mount Lofty Ranges, South Australia, perhamite occurs on a matrix of apatite and quartz (AM 91.1945).

At Tom's quarry, Kapunda, Mount Lofty ranges, South Australia, perhamite is associated with fluellite, minyulite and wavellite (HOM).

At the Emmons pegmatite, Greenwood, Oxford county, Maine, USA, perhamite forms aggregates to 8 mm on albite, quartz or muscovite in miarolytic cavities in an albitised portion of the pegmatite. Recent (2017) finds indicate an unusual association of perhamite with pollucite at the contact of lepidolite veins in pollucite. The Emmons pegmatite is an example of a highly evolved boron-lithium-cesium-tantalum enriched pegmatite (R&M 94.6.513).

At the co-type localities, the Bell pit and the Dunton Gem Quarry, Newry, Oxford county, Maine, USA, perhamite was originally found as late-stage mineralisation in granite pegmatites; subsequently it was found in oxidised zones of ore deposits (Mindat). Associated minerals include siderite, wardite, amblygonite, eosphorite and sphalerite in a vuggy amblygonite-rich pegmatite zone (MM 41.437-442, AM 63.794, HOM).

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