Cacoxenite

phosphate

magnetite

Formula: Fe3+24AlO6(PO4)17(OH)12.75H2O
Hydrated phosphate containing hydroxyl
Specific gravity: 2.2 to 2.6
Hardness: 3 to 4
Streak: Yellow
Colour: Yellow to brownish yellow, reddish orange, golden yellow, deep orange, green; yellow in transmitted light
Solubility: Readily soluble in acids
Environments

Pegmatites
Sedimentary environments (rare)
Hydrothermal environments

Cacoxenite is a common secondary mineral found in oxidised zones of phosphatic magnetite deposits, in iron and manganese bearing novaculite, in phosphate-rich pegmatites, and rarely in iron-rich sediments and soils (Mindat, HOM). Associated minerals include dufrénite, rockbridgeite, beraunite, strengite, wavellite, magnetite and limonite (HOM, Mindat).
At Tom's, Moculta and St John's phosphate quarries in South Australia, cacoxenite has been found replacing small pyrite crystals (AJM 17.1.12).

The type localityis the Hrbek Mine, Svatá Dobrotivá, Central Bohemian Region, Czech Republic.

At the Isom Avants prospect pit in Polk County, Arkansas, USA, cacoxenite has been found in brecciated limonite-stained novaculite with fracture fillings of limonite. The cacoxenite occurs lining cavities in the limonite (AM 51.1811-1814).

At the John A Logan mine, Cripple Creek Mining District, Colorado, USA, cacoxenite occurs in partly oxidised orthoclase - quartz - pyrite rock, following earlier strengite and followed by a member of the rockbridgeite family (MinRec 36.2.164).

At Antwerp, Jefferson county, New York, USA, cacoxenite occurs on earthy hematite (Dana).

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