Anhydrous normal phosphate
Colour: Greenish white, yellow or colourless
Solubility: Slowly soluble in acids
Hurlbutite occurs as a late-stage mineral in complex granite pegmatites. It has
been observed as an alteration product of beryl
At the Viitaniemi pegmatite, Eräjärvi area, Orivesi, Pirkanmaa, Finland, hurlbutite is associated with montebrasite, beryllonite and lithiophilite (HOM).
At the type locality, Chandlers Mill Quarry, Newport, Sullivan county, New Hampshire, USA quartz and albite constitute most of the pegmatite, muscovite and schorl are present in smaller quantities and there are triphylite crystals up to 4 inches long. The pegmatite appears to have been traversed by relatively low-temperature hydrothermal solutions, resulting in the formation of the secondary minerals beryllonite, albite, brazilianite, amblygonite, apatite and siderite. The minerals which have been found directly associated with hurlbutite include muscovite, albite, triphylite, smoky quartz and siderite. The sequence of formation appears to have been muscovite → albite → triphylite → hurlbutite → quartz. The best crystals of hurlbutite are those found embedded in the smoky quartz. Several pseudomorphs of siderite after hurlbutite have been found (AM 37.931-940).
At the Tip Top mine, Fourmile, Custer Mining District, Custer coumty, South Dakota, USA, hurlbutite is associated with tiptopite, englishite and montgomeryite (HOM).
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