Beraunite

phosphate

vivianite

Formula:Fe2+Fe3+5(PO4)4(OH)5.6H2O
Hydrated phosphate containing hydroxyl
Specific gravity: 2.8 to 3.08
Hardness: 3 to 4
Streak: Olive drab (unoxidized)
Colour: Dark greenish-brown, green, grading to grey
Solubility: Readily soluble in hydrochloric acid
Environments

Pegmatites
Sedimentary environments

Beraunite is a secondary mineral found in bog iron ores and as a cement in clays, sands and bone material; it also occurs as an alteration product of triphylite in granitic pegmatites (Mindat, Webmin, HOM).
Associated minerals include vivianite, dufrénite, rockbridgeite, cacoxenite, wavellite, strunzite, ferrostrunzite, ferristrunzite, frondelite, hureaulite, mitridatite, stewartite, laueite, leucophosphite, triphylite and limonite (HOM, Mindat).
Beraunite alters to limonite and alters from vivianite (Mindat).

The type locality is the Hrbek Mine, Svatá Dobrotivá, Beroun District, Central Bohemian Region, Czech Republic.

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