Bermanite

phosphate

triplite

Formula:Mn2+Mn3+2(PO4)2(OH)2.4H2O
Hydrated phosphate containing hydroxyl
Specific gravity: 2.84.to 2.85
Hardness: 3½
Streak: Light red brown
Colour: Reddish-brown; yellowish brown to brownish red with red internal reflections in transmitted light
Solubility: Soluble in nitric acid
Environments

Pegmatites

Bermanite is a late-stage secondary mineral replacing primary phosphate species, usually triplite or lithiophilite, in complex granite pegmatites (Mindat, Webmin, HOM, AM 61.1241-1248).
Associated minerals include triplite, strengite, leucophosphite, hureaulite, lithiophilite, stewartite, sicklerite, rockbridgeite, phosphosiderite, strunzite, switzerite and paulkerrite (HOM, Mindat).

Bermanite is known only from pegmatites which contain oxidised and weathered masses of lithiophilite, triphylite, triplite, or other primary manganese-iron phosphates. Bermanite is one of the last minerals to form during the weathering. It occurs lining seams and cavities and in small masses in the primary mineral or in such secondaries as rockbridgeite, hureaulite, or sicklerite. Phosphosiderite is usually associated with bermanite; stewartite is somewhat less common. Bermanite alters to manganese oxides (AM 52.1060-1066).

At a pegmatite along route 20, 5 miles west of Tanti, Prov. Crodoba, Argentina, bermanite occurs as an alteration product of triplite. Thin crusts of secondary bermanite are associated with phosphosiderite, eosphorite, and a black manganese oxide. Pachnolite has also been observed as white crusts and as colourless crystals on bermanite (AM 53.416-431).

At the McMahon pegmatite near Olary, South Australia, bermanite replaces triplite along fracture surfaces and occurs in association with phosphosiderite, strengite, siderite, hureaulite, rockbridgeite, manganese oxides, and an unknown yellow fibrous mineral (AM 61: 1241–1248).

At the Sapucaia pegmatite, Minas Gerais, Brazil, bermanite occurs sparingly with phosphosiderite coating barbosalite - frondelite rock (AM 52.1060-1066).

At the Marivolanitra pegmatite, Mandrosonoro, Ambatofinandrahana, Madagascar, bermanite occurs with phosphosiderite as an alteration of triplite (AM 52.1060-1066).

At Mangualde, Portugal, bermanite has been found with phosphosiderite coating stewartite and weathered lithiophilite (AM 52.1060-1066).

At the Williams prospect, Coosa County, Alabama, USA, bermanite has been found intimately intergrown with phosphosiderite and manganese oxides in rockbridgeite - lipscombite rock; in some specimens it has been found with stewartite and strunzite as an alteration of hureaulite (AM 52.1060-1066).

At the type locality, the 7U7 Ranch, Bagdad Mine area, Hillside, Eureka District, Yavapai county, Arizona, USA, bermanite occurs in a granite pegmatite associated with triplite, strengite, phosphosiderite, phosphosiderite, paulkerrite, leucophosphite and hureaulite (AM 52.1060-1066, Mindat).

Near the Bagdad Copper Mine, about 25 miles west of Hillside, Arizona, USA, bermanite occurs in a pegmatite in narrow veins crossing triplite (AM 21.656-661), of which it is an alteration product (AM 52.1060-1066).

At the Stewart Mine, Pala, California, USA, bermanite occurs with phosphosiderite, stewartite and hureaulite on lithiophilite and sicklerite (AM 52.1060-1066).

At the Fletcher quarry, North Groton, New Hampshire, USA, bermanite occurs as crusts on rockbridgeite, and as an alteration of hureaulite with phosphosiderite and stewartite (AM 52.1060-1066).

Back to Minerals