Sample Description USGS Spectral Library Version 7

USGS Spectral Library Version 7 Sample Description

Kokaly, R.F., Clark, R.N., Swayze, G.A., Livo, K.E., Hoefen, T.M., Pearson, N.C., Wise, R.A., Benzel, W.M., Lowers, H.A., Driscoll, R.L., and Klein, A.J., 2017, USGS Spectral Library Version 7: U.S. Geological Survey Data Series 1035, 61 p., https://doi.org/10.3133/ds1035
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TITLE: Corundum HS283 DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: HS283.1B, HS283.2B, HS283.3B, HS283.4B

MINERAL_TYPE: Oxide

MINERAL: Corundum (Hematite group)

FORMULA: Al2O3

FORMULA_HTML: Al₂O₃

COLLECTION_LOCALITY: Transvaal

ORIGINAL_DONOR: Hunt and Salisbury Collection

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

This sample was prepared from crystals that were brownish near the surface and blueish-green near in the interior.

Hunt, G.R., J.W. Salisbury, C.J. Lenhoff, 1971, Visible and Near-Infrared spectra of Minerals and Rocks: III. Oxides and Hydroxides. Mod. Geol. 2, pp 195-205.

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

IMAGE_OF_SAMPLE:

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

40 kV - 30 mA, 6.5-9.5 keV additional phase
File: corun283.out, -.mdi
References: Huebner's reference patterns; JCPDS #5-355
Found: corundum, minor diaspore

Comment: Very sharp corundum reflections suggest excellent crystallinity and compositional homogeneity.

END_XRD_ANALYSIS.

COMPOSITIONAL_ANALYSIS_TYPE: None # XRF, EPMA, ICP(Trace), WChem

COMPOSITION_TRACE: None

COMPOSITION_DISCUSSION:

Analysis showed the sample to contain 0.01% Cr; 0.5% Fe; and 0.2% Si, with traces of Ti, V, Mn, Mg, Ca, and Cu. The iron appears to be present on both the ferrous (0.55, 0.45, and 1.1µm absorption features) and ferric (0.7, 0.45, and near 0.4 µm) forms. The Cr³⁺ ion contributes to the 0.4, 0.55 and 0.7 µm (emission) features.

Hunt, G.R., J.W. Salisbury, C.J. Lenhoff, 1971, Visible and Near-Infrared spectra of Minerals and Rocks: III. Oxides and Hydroxides. Mod. Geol. 2, pp 195-205.

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

No cleavage, good parting, uniaxial (-), high relief. All consistent with corrundum. G. Swayze.

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1c2_3_4_ # Corundum HS283.1B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1c2_3_4_ # Corundum HS283.2B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1c2_3_4_ # Corundum HS283.3B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1c2_3_4_ # Corundum HS283.4B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns