Clark and others 2007 USGS Data Series 231
Spectral Library splib06a Sample Description

(For further information on spectroscopy, 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.

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, 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.=
LIB_SPECTRA:	splib06a r 6463			g.s.=