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Clark et. al. 2003 USGS Open File Report 03-395
Spectral Library splib05a Sample Description

(For further information on spectrsocopy, see: http://speclab.cr.usgs.gov)

TITLE: Corundum HS283 DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: HS283

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.

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

40 kV - 30 mA, 6.5-9.5 keVdditional 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, EM(WDS), 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_ # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns

LIB_SPECTRA_HED: where Wave Range Av_Rs_Pwr Comment
LIB_SPECTRA: splib04a r 1282 0.2-3.0µm 200 g.s.= 245 µm
LIB_SPECTRA: splib05a r 2249 0.2-3.0µm 200 g.s.=


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