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(For further information on spectroscopy, see:
http://speclab.cr.usgs.gov)
SAMPLE_ID: HS333
MINERAL_TYPE: Sulfate
MINERAL: Gypsum (Selenite)
FORMULA: CaSO4*2H20
FORMULA_HTML: CaSO4•2H20
COLLECTION_LOCALITY: Washington County, Utah
ORIGINAL_DONOR: Hunt and Salisbury Collection
CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory
ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory
SAMPLE_DESCRIPTION:
"This sample is colorless in hand specimen (colorless gypsum is called
"selenite"), and is white when ground to fine particle size. It also
appears to be quite pure, as its spectrum shows. As in the case of the
previous sample, the near-infrared spectrum displays very prominent
water bands beginning at 1µm and continuing out to 2.5µm."
Hunt, G.R., J.W. Salisbury, and C.J. Lenhoff, 1971, Visible and
near-infrared spectra of minerals and rocks: IV. Sulphides and
sulphates. Modern Geology, v. 3, p. 1-14.
IMAGE_OF_SAMPLE:
END_SAMPLE_DESCRIPTION.
XRD_ANALYSIS:
Pure gypsum
Clark, R.N., King, T.V.V., Klejwa, M., Swayze, G.A., and Vergo, N.,
1990, High spectral resolution reflectance spectroscopy of minerals:
Journal of Geophysical Research, v. 95, no. 8B, p 12,653-12,680.
END_XRD_ANALYSIS.
COMPOSITIONAL_ANALYSIS_TYPE: None # XRF, EM(WDS), ICP(Trace), WChem
COMPOSITION_TRACE: None
COMPOSITION_DISCUSSION:
No compositional analyses.
END_COMPOSITION_DISCUSSION.
MICROSCOPIC_EXAMINATION:
Bimodal grain size distribution:
average gr sz = 242 µm
Sample appears to be pure. Biaxial with good cleavages and low relief. Larger
grains are 15% coated with smaller grains. All this is consistent white pure
gypsum. G. Swayze.
END_MICROSCOPIC_EXAMINATION.
SPECTROSCOPIC_DISCUSSION:
END_SPECTROSCOPIC_DISCUSSION.
SPECTRAL_PURITY: 1a2a3a4a # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
mode 1: 245 µm @ 98 vol%
mode 2: 30 µm @ 2 vol%
LIB_SPECTRA_HED: where Wave Range Av_Rs_Pwr Comment
LIB_SPECTRA: splib04a r 1879 0.2-3.0µm 200 g.s.= 242 µm
LIB_SPECTRA: splib05a r 2992 0.2-3.0µm 200 g.s.=
LIB_SPECTRA: splib06a r 8796 g.s.=
LIB_SPECTRA: splib06a r 8808 g.s.=