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Formula: CaBe2(PO4)2
Anhydrous normal phosphate, beryllium-bearing mineral
Crystal System: Monoclinic
Specific gravity: 2.877 measured, 2.90 calculated
Hardness: 6
Streak: White
Colour: Greenish white, yellow or colourless
Solubility: Slowly soluble in acids
Environments
Hurlbutite occurs as a late-stage mineral in complex granite pegmatites. It has
been observed as an alteration product of beryl
(HOM).
Localities
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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