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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: Calcite HS48 DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: HS48

MINERAL_TYPE: Carbonate

MINERAL: Calcite (Calcite group)

FORMULA: CaCO3

FORMULA_HTML: CaCO3

COLLECTION_LOCALITY: Cherokee County, Kansas

ORIGINAL_DONOR: Hunt and Salisbury Collection

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.

Original sample description and visible-NIR spectrum was published in:

Hunt, G.R., J.W. Salisbury, 1971, Visible and near-infrared spectra of minerals and rocks: II. Carbonates. Modern Geology, v. 2, p. 23-30.

They said: "the sample appears colorless and mineralogically pure. Its spectrum clearly displays the strong carbonate bands from 1.8 to 2.6µ as in the sample above, which are common to most carbonates. It also displays a weak band near 1.1µ and a fall-off in reflectivity less than 0.4µ, which can be attributed to the presence of ferrous ion substituting in small amount for calcium. An analysis of this sample shows that 0.09% of iron by weight is present. This chemical and spectral behavior is quite typical of calcite. Again, pilling of the finest size fraction probably produces the crossover of the spectral curves in the visible."

The spectrum here indicates a pure calcite. The sample appears white with no contaminants under a hand lens.

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.

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

Pure Calcite -- by Norma Vergo

END_XRD_ANALYSIS.

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

COMPOSITION_TRACE: None

COMPOSITION_DISCUSSION:

An analysis of this sample by:

Hunt, G.R., J.W. Salisbury, 1971, Visible and near-infrared spectra of minerals and rocks: II. Carbonates. Modern Geology, v. 2, p. 23-30.

shows that 0.09% of iron by weight is present.

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

Bimodal grain size distribution:

population 1 210µm 98 vol%
population 2 20µm 2 vol%

avg. grain size of populations = 208µm

Pure sample. Clear rhombs. Large grains 40% coated with smaller grains. Readily fizzes in dilute 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 799 0.2-3.0µm 200 g.s.= 208 µm
LIB_SPECTRA: splib05a r 1508 0.2-3.0µm 200 g.s.=


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