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Formula: (H2O)2Mn2Ti2Fe3+(PO4)4(OF)(H2O)10.4H2O
Hydrated phosphate, paulkerrite group,
manganese- and titanium- bearing
mineral
Crystal system: Orthorhombic
Specific gravity: 2.37 calculated
Hardness: 2½ to 3
Streak: White
Colour: Light greenish yellow to light brown
Luminescence: Not fluorescent under UV
Environments
Benyacarite is a rare secondary mineral in complex
zoned granite
pegmatites, associated with
phosphosiderite,
strengite, pachnolite,
apatite and torbernite
(HOM).
Localities
The type locality is El Criollo Mine, Cerro Blanco pegmatite district, Tanti, San Roque District, Punilla Department,
Córdoba Province, Argentina. Bedrock in the district includes a group of
granitic
pegmatites that have been mined for
feldspar, quartz,
beryl and minor
columbite-tantalite. The
pegmatites are characterised by high contents of phosphate
minerals, both primary
(triplite and apatite) and
secondary. Triplite
is the most common primary phosphate mineral, occurring in
quite large nodules, up to 4 m across, , commonly showing alteration along the surface and fractures. Together with
the triplite relics, there are considerable amounts of
secondary phosphates, such as
phosphosiderite, strengite
and rockbridgeite, together with minor quantities of
lipscombite, dufrénite,
libethenite, bermanite and
hentschelite. Some fluorine-rich species such as
fluellite and pachnolite have
also been observed, suggesting that a fluorine-rich paragenesis migbt be essential for the formation of
benyacarite and of the paulkerrite group minerals in
general. The most common secondary phosphate is
phosphosiderite, a mineral mainly pink in colour that occurs both as
idiomorphic crystals and in massive form, and also as porous bluish purple masses in a matrix to the
benyacarite. Small crystals of benyacarite have also been observed implanted on
strengite and pachnolite in a
mineral association dominated by secondary
apatite, in some cases accompanied by scarce dark purple
phosphosiderite and
torbernite. Massive benyacarite was identified in continuity with
phosphosiderite; it can be distinguished by its green colour in
contrast to the pink colouration of the earlier formed
phosphosiderite.
Benyacarite occurs in euhedral, commonly tabular, crystals ranging from 0.2 to 0.3 mm in size
(CM 35.3.707-712).
Benyacarite from El Criollo Mine -
Image
At the Hagendorf South Pegmatite, Hagendorf, Waidhaus, Neustadt an der Waldnaab District, Upper Palatinate,
Bavaria, Germany, yellow benyacarite occurs on green
rockbridgeite
(Mindat photo).
Benyacarite from Hagendorf - Image
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