Anhydrous normal phosphate, triphylite group, forms a series with ferrisicklerite
Specific gravity: 3.2 to 3.4
Streak: Light ochre brown
Colour: Dark brown to yellow-brown
Solubility: Soluble in acids
Sicklerite is found in granite pegmatites, where it occurs only as a late-stage
alteration product of triphylite and
lithiophilite, commonly as rims around partly altered masses (Mindat, HOM).
At the type locality, the Stewart Mine, Pala, San Diego county, California, USA, sicklerite occurs in a lithium-bearing pegmatite associated with hureaulite, stewartite, phosphosiderite, jahnsite and phosphosiderite (Dana, Mindat, HOM).
At the Emmons pegmatite, Greenwood, Oxford county, Maine, USA, sicklerite occurs only as massive material formed by the oxidation of lithiophilite. The Emmons pegmatite is an example of a highly evolved boron-lithium-cesium-tantalum enriched pegmatite (R&M 94.6.515).
Sicklerite alters to the heterosite - purpurite series by oxidation of the Mn2+ to Mn3+ and leaching of the lithium (Mindat).
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