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Alluaudite

#PD35933

Alluaudite

#PD35933
Availability
Sold
Size
6 x 4 x 5 cm - Sm Cabinet 
Formula
(Na,Ca)2(Mn,Mg,Fe2+)(Fe3+,Mn2+)2(PO4)3 (RRUFF)
Locality
Pleasant Valley mine, Custer Co., South Dakota, United States
Tagged
phosphate , pegmatite mineral

Tough, compact, fine grained mineral, which usually does not yield secondary phosphates. 

Alluaudite is more of a metasomatic exchange product than it is a primary phase with lithium in parent triphyllite being replaced by Na and Ca, according to Paul Moore in Min. Record (1973). Alluaudite occurs in many pegmatites but may also occur in phosphorites. 

Alluaudite

Formula
(Na,Ca)2(Mn,Mg,Fe2+)(Fe3+,Mn2+)2(PO4)3 
Crystal System
Monoclinic 
Crystal Habit
Platy, Fibrous, Nodular 
Cleavage
Good, Good, None 
Color
brownish yellow, green, yellow, black 
Streak
brownish yellow 
Class
Monoclinic - Prismatic 
Hardness
5-5.5 

Data courtesy of Webmineral.

Collection
Phillips Collection

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