Images
Formula: (Mn2+,Ca)Mn2+(Fe2+,Mn2+,Mg)2(Al,Fe3+)2(PO4)4(OH)2.8H2O
Hydrated phosphate, whiteite subgroup,
jahnsite group,
manganese-bearing mineral
Crystal System: Monoclinic
Specific gravity: 2.81 measured, 2.83 calculated
Hardness: 3½
Streak: White
Colour: Very pale yellow to lemon-yellow, brownish yellow
Common impurities: Mg
Environments
Localities
At the type locality, the Cubos-Mesquitela-Mangualde area, Mangualde, Viseu, Portugal,
granites were emplaced in mica
schist and gneiss. A
complex of zoned veins of pegmatite cuts the
granites. Starting from the
granite, their zoning is as follows:
an aplitic periphery 2 cm thick,
a fine-grained pegmatite with abundant
mica, quartz and
feldspar 20 cm thick,
a coarse-grained pegmatite with
smoky quartz, pink orthoclase and
white plagioclase 300 to 350 cm thick,
a coarse-grained pegmatite like the previous one, bearing
uraniferous micas,
lithium - manganese -
iron bearing phosphates (nodules) and
manganese oxides, 800 cm thick
The samples came from phosphatic nodules of one of the thicker veins within a
two-mica granite.
Rittmannite was found on two small (1 x 1 x 1 cm3) phosphate specimens, consisting of crystallised
red-brown, skeletal kryzhanovskite, black needle-like
frondelite, pink vitreous
hureaulite and white massive
adularia. It is likely that rittmannite was the last to form in this
sequence. The average crystal dimensions are 0.3 x 0.3 x 0.04 mm3
(CM 27.3.447-449).
Rittmannite from the Cubos-Mesquitela-Mangualde
area - Image
Back to Minerals