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0 item @ $0.00  

Frondelite

#41603

Frondelite

#41603
Availability
Sold
Size
6.5 x 4.5 x 4 cm - Sm Cabinet 
Formula
Mn2+Fe3+4(PO4)3(OH)5 (RRUFF)
Locality
Tip Top mine, Custer Co., South Dakota, United States
Tagged
phosphate , pegmatite mineral

Frondelite is the Mn analogue of Rockbridgeite. My only basis for calling this "Frondelite" is that it is brown. Rockbridgeite is usually black and Frondelite is usually brown. And of course there's always exceptions and Rockbridgeite has shades of green and Frondelite can be black. Someday I'll sit down with my pocket EDS and analyze all the zones of chemical variations.  

The best Rockbridgeite is acicular free-standing radial groups in altered Triphylite vugs. Rockbridgeite also occurs as embedded hairlike masses just like this specimen but black. This piece is mainly altered primary Triphylite maybe a metasomatic product, which is my reasoning for placing it in this gallery. 

Frondelite

Formula
Mn2+Fe3+4(PO4)3(OH)5 
Crystal System
Orthorhombic 
Cleavage
Perfect, Distinct, Distinct 
Luster
Vitreous - Dull 
Color
brown, brown green, brownish black, green black, dark green 
Streak
brownish gray 
Class
Orthorhombic - Dipyramidal 
Fracture
Brittle - Uneven 
Hardness
4.5 

Data courtesy of Webmineral.

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