U.S. Geological Survey home page


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: Diaspore HS416 DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: HS416

MINERAL_TYPE: Hydroxide

MINERAL: Diaspore

FORMULA: AlO(OH)

FORMULA_HTML: AlO(OH)

COLLECTION_LOCALITY: Rosebud, MO

ORIGINAL_DONOR: Hunt and Salisbury Collection

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

"Dimorphic with Boehmite. This sample is impure and is a mixture of bauxite minerals including gibbsite, kaolinite and a very small amount of a ferruginous material. At wavelengths longer than 1.3µm the reflectance of the sample decreases. The sample has a 1.4 µm absorption (overtone of the hydroxyl) and a 1.8 µm absorption which is believed to be a displaced 1.9µm resulting from the presence of a free H2O molecule."

Hunt, G.R., J.W. Salisbury, and C.J. Lenhoff, 1971, Visible and near-infrared spectra of minerals and rocks: III. Oxides and hydroxides. Modern Geology, v. 2, p. 195-205.

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS: Pure diaspore.

Konnert, Judith and Marta Flohr, 1992, unpublished data, USGS Reston, VA.

END_XRD_ANALYSIS.

COMPOSITIONAL_ANALYSIS_TYPE: None # XRF, EM(WDS), ICP(Trace), WChem

COMPOSITION_TRACE: None

COMPOSITION_DISCUSSION:

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

Bimodal grain size distribution:
population 1 = 268 µm at 92 vol%
population 2 = 10 µm at 8 vol%

average grain size = 257 µm

Small grains coat larger grains. Large grains are translucent and this makes it difficult to obtain optical properties. I recommend that this sample be x-rayed for proper identification. No fizz with HCl. G. Swayze.

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1a2_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 1388 0.2-3.0µm 200 g.s.= 257 µm
LIB_SPECTRA: splib05a r 2333 0.2-3.0µm 200 g.s.=


USA.gov logo  Take Pride in America button