Specimen data for Tantalite-(Fe)

Tom Mortimer catalog number: p/o 1491

Identification method: A Kerry Day qualitative EDS analysis gave:
Ta (1.71) = 1369; Nb (2.17) = 421; Ti (4.51) = 122; Mn (5.90) = 232; Fe (6.40) = 414; Background 3/10 = 78/52
(Fe,Mn)(Ta,Nb,Ti)2 oxide
A follow-up quantitative EDS analysis (set 28, BC380) indicated an APFU of (Fe_0.65,Mn_0.4)(Nb_0.29,Ta_0.1)O₆ , normalized for 0.65 atoms of Fe, so Fe + Mn = 1.0.
This computed APFU is a bit confounding, with the EDS plot showing Ta >> Nb. The APFU indicates this is Columbite-(Fe).
Yet another EDS analysis BC451, also had a Ta plot peak >> the Nb peak, but the tabulated element atomic percents has Nb > Ta. The element atomic percent computation for the heavy element tantalum is becoming suspect. For this BC451 analysis, the "Eu" is likely a miss-identification of a second Mn peak and the Cu peak is likely a low amplitude Ta peak.
A George Adleman Raman analysis supported a tantalite identification: Raman Plot 1 , Raman Plot 2 . The second Raman plot compares this catalog #1491 with a mixture of minerals: Tantalite-Fe 67%, Columbite 2%, and Eulytine 2%. The mixture weights are of the Raman signal strengths needed to make the composite of the RUFF references a best match - to the extent "explained" (in this case "81%"). [ga] "There are a lot of assumptions in this which make the lower percentage items less likely to be accurate - especially < 10% ones. So, I would say there is a very high likelihood that BC451 is Tantalite-Fe with some likelihood that Columbite is also present"

Notes: