TITLE: Anorthite HS349 Plagioclase DESCRIPT
MINERAL: Anorthite (Plagioclase, Ca end member)(Feldspar group)
COLLECTION_LOCALITY: Grass Valley, California
ORIGINAL_DONOR: Hunt and Salisbury Collection
CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory
ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory
The original sample and vis-nir spectrum was described in:
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.
The authors reported that they removed most of the pyroxene from the original sample, and none is obvious in the visible-NIR spectrum. There are a few dark grains in the bulk sample, but << 1%. The authors also reported that original sample contained some diopside and magnetic impurities but that the magnetic impurities were removed.
Some alteration is evident by the 2.3-µm region absorption bands in the spectrum. Roger N. Clark
Anorthite + (medium) Chlorite + (small) 9.4 angstrom peak + 2.778 angstrom (Microcline?) - by Norma Vergo
Notes: the microscopic analysis shows that the impurities can't be detected, so the sample should be spectrally pure in the visible. There is a 2.3-µm band and weak 1.4 band, so some impurities do show there.
COMPOSITIONAL_ANALYSIS_TYPE: None # XRF, EM(WDS), ICP(Trace), WChem
Clean, clear to frosted rectangular grains. Very pure, no visible alteration, synthetic twining. G. Swayze
av gr sz = 280µm
Notes: XRD indicated chlorite and others present, but they can't be detected optically, so the vis spectrum should be spectrally pure. There is a 2.3-µm band and weak 1.4 band, so some impurities do show weakly in the nir.
LIB_SPECTRA_HED: where Wave Range Av_Rs_Pwr Comment
LIB_SPECTRA: splib04a r 479 0.2-3.0µm 200 g.s.= 280 µm
LIB_SPECTRA: splib05a r ____ 0.2-3.0µm 200 g.s.=
LIB_SPECTRA: splib06a r ____ 1.5-25µm 250 g.s.=