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Formula: CaLa(Al2Fe2+)[Si2O7][SiO4]O(OH)
Sorosilicate (Si2O7 groups), allanite group of
the epidote supergroup,
lanthanum-bearing mineral
Crystal System: Monoclinic
Specific gravity: 3.93 measured, 3.94 calculated
Hardness: 6
Streak: Brown
Colour: Black, with brownish reflections
Luminescence: Not fluorescent under UV
Solubility:
Environments
Plutonic igneous environments
Pegmatites
Metamorphic environments
Localities
At Serifos island, Cyclades, Greece, allanite-(La) occurs in skarn
(Dana).
At the type locality, the Buca della Vena Mine, Stazzema, Lucca Province, Tuscany, Italy, allanite-(La) is
closely associated with calcite and
baryte, and occurs within baryte veins
cutting a dolomitic metamorphosed
limestone in a specific zone of the mine known as “Castello”. The
Buca della Vena mine is a well-known small mineralised orebody of microcrystalline
hematite, magnetite,
pyrite and baryte. At this locality,
tiny black prismatic crystals of allanite-(Ce) were also found in other
quartz veins located in a different part of the mine;
allanite-(Ce) occurs there together with
monazite-(Ce), pyrite, anatase,
gypsum and diadochite
(CM 44.1.63-68).
At the Nueva Vizcaya mine, Badajoz, Spain, crystals of allanite-(La) occur in
skarn
associated with magnetite,
actinolite,
albite, epidote, and
titanite (R&M 86.5.451). Although allanite-(La) is very rare
generally, it is
relatively common on a particular part of the dump at the Nueva Vizcaya mine, embedded in
calcite
(Min Rec 33-6.491-494).
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