COLLECTION_LOCALITY: New Mexico
ORIGINAL_DONOR: Gem Show purchase
CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory
ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory
This sample was purchased at a Gem show. The sample is probably from New Mexico, but that is not 100% certain. The sample appears white with no contamination. The reflectance spectrum indicates virtually no contamination. There are very weak bands in the visible, possibly indicating some iron, but it is not apparent visually under a hand lens.
40 kV - 30 mA, 6.5-9.5 keV
Reference: JCPDS #6-226; Huebner's reference patterns
Sought but not found: gypsum
Comment: Extremely sharp reflections indicate good crystallinity. Excellent match up with the JCPDS card.
J.S. Huebner, J. Pickrell, and T. Schaefer, 1994, written communication.
COMPOSITIONAL_ANALYSIS_TYPE: None # XRF, EPMA, ICP(Trace), WChem
Bimodal grain size distribution:
population 1 170µm 82 vol%
population 2 10µm 18 vol%
avg. grain size of populations = 154µm
Prismatic grains, good cleavage, light blue color in hand specimen. Trace of opaques. High birefringence and biaxial (+). All these are consistent with anhydrite. Twinning parallel to long dimension. Smaller grains adhere extensively to larger grains. G. Swayze
SPECTRAL_PURITY: 1a2a3a4_ # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns