Locality: Government Pit, Albany, NH
Specimen Size: 1 mm crystal
Field Collected: Gene Bearss (1986)
Catalog No.: A Gene Bearss collection specimen
Notes: Identification by Gene Bearss
Locality: Government Pit, Albany, NH
Specimen Size: 2 mm field of view. Microlite and cassiterite on columbite.
Field Collected: Gene Bearss (1980)
Catalog No.: A Gene Bearss specimen
Notes:
Locality: Parker Mtn. Mine, Center Strafford, NH
Specimen Size: 0.6 mm microlite crystal with smaller daughter crystal on top
Field Collected: Gene Bearss
Catalog No.: u1432
Notes: I found this small crystal difficult to photograph. Many faces are slightly rounded and lack sharp definition.
Gene had this labeled as pharmacosiderite. Pharamacosiderite is reported from the Parker Mtn. Mine, but specimen examples are very rare to non-existant. The crystal color and luster are reasonable for pharmacosiderite, however pharmacosiderite crystals are usually cubes. I could not orient this small crystal to see the cube form.
A January, 2014 EDS analysis showed these small crystals to be microlite. This EDS instrument has a very low response to light elements. The analyst stated: "I can imagine a small Na peak at 1.04 KeV"
Quantitative EDS analyses BC355, BC355A, October 2019, also supported a microlite identification. The APFU's computed from these (carbon tape mounted grain) analyses gave:
BC255 -> NaCa1.05Ta0.31Nb0.07Cu0.41Si0.89F0.38O27 , normalized for one Na.
BC255A -> NaCa1.10Ta0.32Nb0.06Fe0.26Ti0.11Al0.13Si1.01O28.5 , normalized for one Na.
Some comments on the BC355,A analyses: Mindat.org states that Pb and Fe are sometimes seen as substitutes. The Ta + Nb totals for these analyses are low for microlite, and the oxygen is very high. The silicon (Si) is suspected to be a miss-ID by the EDS element matching software, the thinking is that the Si (at 1.74 KeV) is really part of a Ta peak at 1.71 KeV. The Cu response around 8.05 KeV in the BC355 analysis is most likely a Ta peak at 8.15 KeV.
The Ca, Na, Ta, Nb element content for both analyses were very consistant.
Locality: Parker Mtn. Mine, Center Strafford, NH
Specimen Size: 0.4 mm microlite crystal
Field Collected: Gene Bearss
Catalog No.: u1432
Notes: