SAMPLE_ID: HS294.1B, HS294.2B, HS294.3B, HS294.4B, HS294.6
MINERAL: Cummingtonite (Amphibole group)
COLLECTION_LOCALITY: Lead, SD
ORIGINAL_DONOR: Hunt and Salisbury Collection
CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory
ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory
Forms series with Magnesiocummingtonite and Grunerite.
"I-13 Cummingtonite 294B--Lead, S. Dakota. (Mg, Fe2+)5(Si8O22)(OH)2: This amphibole has the same composition as anthophyllite, but is monoclinic rather than orthorhombic in crystal form. Its spectrum is a relatively smooth curve in which there is no evidence of hydroxyl bands, but in which the main feature is a broad ferrous iron band near 1.0µ. The lack of hydroxyl bands in what appears to be a rather pure amphibole in hand specimen is something that we cannot explain. Reflectivities I through IV are 40%, 24%, 12%, and 8% at 0.75µ, and 32%, 15%, 6%, and 4% at 1.0µ. The sample is a dark greenish gray. The low reflectivities are a function of this sample darkness, not of contamination with opaques."
Hunt, G.R., J.W. Salisbury, and C.J. Lenhoff, 1973, Visible and near-infrared spectra of minerals and rocks: VI. Additional silicates. Modern Geology, v. 4, p. 85-106.
Grain size fractions are indicated by the extension after the sample number:
.1B = <5 µm
.2B = <74 µm
.3B = 74-250 µm
.4B = 250-1200 µm
.6 = cut slab
Cummingtonite + quartz + biotite + chlorite + others (Norma Vergo)
COMPOSITIONAL_ANALYSIS_TYPE: None # XRF, EPMA, ICP(Trace), WChem
Sample has two different amphiboles, one green and the other clear in about equal proportions. Sample also contains significant quartz and trace garnet? G. Swayze.
SPECTRAL_PURITY: 1c2_3_4_ # Cummingtonite HS294.1B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1c2_3_4_ # Cummingtonite HS294.2B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1c2c3c4c # Cummingtonite HS294.3B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1c2_3_4_ # Cummingtonite HS294.4B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1c2_3_4_ # Cummingtonite HS294.6 # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns