Locality: Charles Davis Mine, N. Groton, NH
Specimen Size: 1.4 field of view
Field Collected: Bob Wilken
Catalog No.: A Bob Wilken specimen and photo
Notes: Rockbridgeite is rare at the Charles Davis Mine. Mindat.org does not include it in their species list for the mine (June, 2020).
Other phosphate minerals are present in this view. Bob states the tiny yellow sprays may be childrenite and the gray-tan balls whitmoreite.
Locality: Palermo Mine, Groton, NH
Specimen Size: 1.5 cm field of view
Field Collected: From a tub gifted by Bob Whitmore
Catalog No.: u2539
Notes: There are now three "flavors" of rockbridgeite:
Rockbridgeite: Fe2+Fe3+4(PO4)3(OH)5
Ferrirockbridgeite: (Fe3+0.67 □ 0.33)2Fe3+3(PO4)3(OH)4(H2O) Unsure of the meaning of □ .
Ferrorockbridgeite: (Fe2+,Mn2+)2Fe3+3(PO4)3(OH)4(H2O) Ferrorockbridgeite was first described in 2018, ferrirockbridgeite in 2019.
The type locality for ferrirockbridgeite is the Palermo #1 Mine.
An email from Tony Kampf, one of the co-authors in both these new species, stated:
"Ferrirockbridgeite does generally exhibit more of a red-brown color, so your specimen could exhibit both rockbridgeite and ferrirockbridgeite.”
So a risky rule of thumb might be bronze-colored rockbridgeite is ferrirockbridgeite.