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: Albite HS66 Plagioclase DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: HS66

MINERAL_TYPE: Tectosilicate

MINERAL: Albite (Plagioclase, Na end member)(Feldspar group)

FORMULA: NaAlSi3O8

FORMULA_HTML: NaAlSi3O8

COLLECTION_LOCALITY: Amelia, Virginia

ORIGINAL_DONOR: Hunt and Salisbury Collection

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

"This sample of albite is quite pure, and consequently has a high reflectivity throughout this wavelength range (.4-2.5 µm). The only two bands displayed (near 1.4 and 1.9 µm) are due to water in fluid inclusions."

Hunt, G.R., J.W. Salisbury, 1970, Visible and near-infrared spectra of minerals and rocks: I. Silicate minerals. Modern Geology, vol. 1, pp 283-300.

White color, 74-250µm sieve interval. This is the sodium end member of the albite-anorthite series.

Also apparent in the spectrum is a weak 2.2-µm absorption, apparently due to some alteration that is not detectable under microscopic examination. Roger N. Clark

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

Albite + trace mica. (Norma Vergo)

END_XRD_ANALYSIS.

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

COMPOSITION_TRACE: None

COMPOSITION_DISCUSSION:

No compositional analyses available

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

Bimodal grain size distribution:

population 1 = 190µm 99 vol%
population 2 = 8µm 1 vol%

avg. grain size of populations = 189µm

Pure feldspar. Larger grains cleavage and fracture bounded with 20% of their surfaces covered by smaller grains. No mica visible in either grains size fraction. 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 117 0.2-3.0µm 200 g.s.= 189 µm
LIB_SPECTRA: splib05a r 168 0.2-3.0µm 200 g.s.=


USA.gov logo  Take Pride in America button