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: Calcite WS272 DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: WS272

MINERAL_TYPE: Carbonate

MINERAL: Calcite (Calcite group)

FORMULA: CaCO3

FORMULA_HTML: CaCO₃

COLLECTION_LOCALITY: Tunguska, Siberia, USSR

ORIGINAL_DONOR: Wards Scientific

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

Forms series with Rhodochrosite. Trimorphous with Aragonite and Vaterite.

This sample was ground from a beautiful single crystal of type Iceland Spar. The single crystal appeared pure, and the visible-NIR spectrum appears pure.

See Clark, R.N., T.V.V. King, M. Klejwa, G. Swayze, and N. Vergo, 1990, High spectral resolution reflectance spectroscopy of minerals: J. Geophys Res. 12653-12680.

IMAGE_OF_SAMPLE:

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

Calcite + small amount of "other" -- by Norma Vergo However, there is no "other" apparent in the single crystals or the ground sample. -- Roger N. Clark

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 450µm 85 vol%
population 2 15µm 15 vol%

avg. grain size of populations = 410µm

Pure sample from single crystal. Rhombic cleavage, twins, uniaxial, very high birefringence, fizzes readily in dilute HCl. Smaller grains adhere to larger grains covering 40-80% of larger grains cleavage surfaces.

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

LIB_SPECTRA_HED:	where	Wave Range	Av_Rs_Pwr	Comment
LIB_SPECTRA:	splib04a r 787	0.2-3.0µm	200	g.s.= 410 µm
LIB_SPECTRA:	splib05a r 1520	0.2-3.0µm	200	g.s.=
LIB_SPECTRA:	splib06a r 4159			g.s.=
LIB_SPECTRA:	splib06a r 4172			g.s.=