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Formula: BaCa[Be4P4O16].6H2O
Hydrated phosphate, barium- and
beryllium- bearing mineral
Crystal System: Monoclinic
Specific gravity: 2.58 calculated for the empirical formula
Colour: Colourless to snow-white
Luminescence: Not fluorescent under UV
Environments
Limousinite is a relatively new mineral, approved in 2019 and to date (February 2024) reported only
from the type locality.
Localities
At the type locality, the Vilatte-Haute Quarry, Vilatte Quarries, Chanteloube, Razès, Bellac, Haute-Vienne,
Nouvelle-Aquitaine, France, limousinite occurs at the historical
pegmatite phosphate locality.
Primary nodular
lithium - manganese -
iron phosphates (mostly triplite,
alluaudite and heterosite)
embedded in the beryl-bearing
pegmatite are locally associated with
pyrite and löllingite. Within
these minerals, supergene alteration created dissolution vugs
containing free-grown microminerals, including numerous
secondary phosphates and arsenates:
arthurite, bendadaite,
beraunite, cacoxenite,
dufrénite, fluellite,
frondelite, goudeyite,
greifensteinite,
hureaulite,
jahnsite-(CaMnFe),
leucophosphite,
metazeunerite, olivenite,
pharmacosiderite,
phosphosiderite,
rittmannite, scorodite,
stewartite, strengite,
symplesite, whitmoreite,
the new manganese equivalent of
bendadaite, and the (FeFeFe)-equivalent of
whiteite.
Limousinite was discovered in these alteration vugs, in close association with microcrystalline pale brown
greifensteinite, black amorphous vitreous manganeseoxyhydroxide,
and earlier triplite and quartz.
The limousinite was probably formed by acid leaching (from
arsenopyrite and löllingite
alteration) of fluorapatite and
beryl and subsequently crystallised in vugs. The
barium source remains unknown.
Limousinite forms isolated, partly corroded, colourless to snow-white
prismatic crystals up to 0.9 mm long, with rhombic cross sections
(CM 58.6.815-827).
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