SAMPLE_ID: HS338.3B, HS338.6
ORIGINAL_DONOR: Hunt and Salisbury Collection
CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory
ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory
Rhodochrosite, MnCO3, is a comparatively rare carbonate mineral, usually occurring in hydrothermal veins with ores of silver, lead and copper, and with other manganese minerals. Divalent iron and calcium substitute for manganese, and a complete solid solution series appears to extend to siderite and calcite.
Hunt, G.R., J.W. Salisbury, 1971, Visible and near-infrared spectra of minerals and rocks: II. Carbonates. Modern Geology, v. 2, p. 23-30.
Grain size fractions are indicated by the extension after the sample number:
.3B = 74-250 µm
.6 = cut slab
40 kV - 30 mA, 7.3-9.5 keV
File: rhdch338.out, -.mdi
References: Huebner's reference patterns
Found: Rhombohedral carbonate, minor quartz, unidentified reflections at 2.88 Angstroms (moderately strong), 2.61i Angstroms (moderately weak), and 1.406 Angstroms (weak)
Sought but not found: pyrolusite, manganite, Mn-silicates
Comment: The carbonate lattice spacing's are consistent with MnCO3-rich composition. Sharp, well-formed peaks suggest good degree of crystallization and compositional homogeneity. The carbonate lattice spacing's are consistent with MnCO3-rich composition, probably in solid solution with magnesite and/or siderite.
J.S.Huebner, J. Pickrell, T. Schaefer, written communication(USGS 1994)
COMPOSITIONAL_ANALYSIS_TYPE: None # XRF, EPMA, ICP(Trace), WChem
SPECTRAL_PURITY: 1b2b3b4_ # HS338.3B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1b2_3_4_ # HS338.6 # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns