Locality: Rice Mine, Groton, NH
Specimen Size: 3.0 mm field of view
Field Collected: John Reiner # 8730. Mounted by Steve Cares 1989.
Catalog No.: Harvard specimen # 9482
Notes: A visual ID. This soft, green-blue mineral compares favorible with my Palermo Mine example.
Locality: Keyes Mine, Orange, NH
Specimen Size: 2.8 mm field of view, top photo.
Field Collected: Tom Mortimer
Catalog No.: u185
Notes: [tm] I have had this cataloged and labeled as rockbridgeite since I collected it in the 1980's. It was a visual identification. In the past decade I have become aware of the frondelite species, chemically close to rockbridgeite, but with Mn replacing about 20% of the Fe. My analyzed NH frondelite is greenish when compared to black NH rockbridgeite. I have two of thse specimens. In both, these greenish balls are in voids of quartz that appear to have been formally occupied by another mineral, perhaps pyrite.
A May 2021 EDS analysis (BC379 set 28) indicated just an iron phosphate. The chemistry indicated by the analysis is Fe2.94P3.0O16.7 . This would be close to rockbridgeite, but also close to barbosalite. The greenish color is more consistent with barbosalite than rockbridgeite.
Rockbridgeite chemistry: Fe2+Fe3+4(PO4)3(OH)5
Barbosalite chemistry: Fe2+Fe3+2(PO4)2(OH)2
No Mn was detected, so not frondelite.
A carbon tape mounted grain from this specimen was analyzed as BC421, set 31. This analysis (2 probes) gave a confusing result that was inconsistent with analysis BC379.... and was likely a mix of two or more species in the sample.