MINERAL_TYPE: Carbonate - Hydroxide
COLLECTION_LOCALITY: Dark Star Mine, Darby, Montana, USA
ORIGINAL_DONOR: Wards Scientific
CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory
ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory
SAMPLE_DESCRIPTION: Pink massively textured sample.
XRD detected dominant calcite, major barite, and minor La-bearing ancylite. (R. Driscoll).
COMPOSITIONAL_ANALYSIS_TYPE: None # XRF, EPMA, ICP(Trace), WChem
SPECTROSCOPIC_DISCUSSION: Sample has a number of sharp spectral absorptions (f-f orbital electronic transitions) throughout the 0.35 to 1.7 micron range presumably due to variable proportions of lanthanide series rare earth elements (i.e., Nd, and others). Bands at 0.579, 0.746, 0.801, and a triplet centered about 0.87 microns resemble similar absorptions in neodymium oxide. Between 1.54 and 1.714 microns are a series of overlapping Pr and Sm bands. Combination and overtone bands of the CO3 fundamental are typically seen near 2.34 and 2.16 microns for calcite. The ancylite spectrum shows a very weak 2.16 micron band and in the 2.34 micron region of the spectrum has an uncharacteristic doublet that could be influenced by REE absorptions. The presence of numerous shoulders on these bands may indicate the presence of additional lanthanide series elements. SEM analysis confirmed the presence of calcite, barite and ancylite but the ancylite was the only mineral phase to have REE bands in the EDS spectrum. Thus, the REE f-f bands observed in the spectra are due to ancylite. (G. Swayze and T. Hoefen)
SPECTRAL_PURITY: 1c2_3_4_ # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns