Radial Cacoxenite Crystals

Radial Cacoxenite Crystals
Radial Cacoxenite Crystals. La Paloma Mine, Zarza la Mayor, Mancomunidad Rivera de Fresnedosa, Cáceres, Extremadura, Spain. Photo: Rewitzer Christian.


Cacoxenite is an iron aluminum phosphate mineral. It’s associated with iron ores.

It was first described in 1825 for an occurrence in the Hrbek Mine, Bohemia, Czech Republic. It occurs as a secondary phase in oxidized magnetite and limonite deposits. It also occurs in novaculites and in iron and phosphorus rich sediments.

Often times, it forms as fuzzy brownish yellow, brown, yellow, or gold radiated tufts or strands. It may also appear as reddish orange or greenish yellow. The cacoxenite is occasionally referred to cacoxene or cacoxitite.

Cacoxenite is associated with iron ores. The name comes from the Greek κăκός for "bad" or "evil" and ξένος for "guest" because the phosphorus content of cacoxenite lessens the quality of iron smelted from ore containing it.

Formula: Fe3+24Al(PO4)17O6(OH) 12· 17(H2O)
System: Hexagonal
Colour: Yellow to brownish ...
Hardness: 3 – 4
Association: Dufrenite, rockbridgeite, beraunite, strengite, wavellite, magnetite, "limonite".
Occurrence: A common accessory mineral in oxidized magnetite and "limonite" iron ores; in Fe,Mn-bearing novaculites; a rare constituent of iron-rich sediments and soils.