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Formula: CaMn(Fe3+,Mn)2Fe3+2(PO4)4(OH)3.7H2O
Valence: CaMn2+(Fe3+,Mn2+)2Fe3+2(PO4)4(OH)3.7H2O
Hydrated phosphate, jahnsite subgroup,
jahnsite group,
manganese-bearing mineral
Crystal system: Monoclinic
Specific gravity: 2.6 measured, 2.682 calculated
Hardness: 4½
Colour: Golden brown, orange-brown
Luminescence: Not fluorescent under UV
Common impurities: Mg
Environments
Localities
At the type locality, the Hagendorf South Pegmatite, Hagendorf, Waidhaus, Neustadt an der Waldnaab District, Upper
Palatinate, Bavaria, Germany, keckite occurs as late-stage oxidised mineralisation in
secondary phosphate-rich
granite
pegmatites. It forms crusts of yellow-brown to golden brown
indistinct crystals up to 2 mm long, formed by the weathering of
phosphophyllite or
rockbridgeite. Associated minerals include
apatite, hureaulite,
phosphophyllite,
phosphosiderite,
rockbridgeite, scholzite,
strengite and vivianite
(AM 64.1330-1331, Mindat)
Keckite from the Hagendorf South Pegmatite -
Image
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