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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: Andalusite NMNHR17898 DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: NMNH17898

MINERAL_TYPE: Nesosilicate

MINERAL: Andalusite

FORMULA: Al2SiO5

FORMULA_HTML: Al2SiO5

COLLECTION_LOCALITY: St. Theresa, Espirito Santo, Brazil

ORIGINAL_DONOR: National Museum of Natural History

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

Forms series with Kanonaite. Trimorphous with Kyanite and Sillimanite.

The structure consists of chains of AlO6 octahedra parallel to c, cross-linked by SiO4 tetrahedra and AlO5 polyhedra. Andalusite is typically formed in the contact aureoles of igneous intrusions in argillaceous rocks.

"Results of petrographic examination: Sample is composed of two crystals, one clear and one pale pink. Both appear pure, both 1 x 0.5 cm. Examination under petrographic microscope indicates pure and clean sample. Sample grains chosen for microprobe analysis are clear but with poor polish in part. "

Salisbury, J. W., Walter, L. W., and Vergo, N., 1987, Mid-Infrared (2.1-25µm) Spectra of Minerals: First Edition, U.S. Geological Survey Open File Report 87-263.

There are weak absorption features near 2.2 and 2.35 µm due to trace alteration not seen by other methods. -Roger N. Clark

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

Pure. (Norma Vergo)

Pure.: Salisbury, J. W., Walter, L. W., and Vergo, N., 1987, Mid-Infrared (2.1-25µm) Spectra of Minerals: First Edition, U.S. Geological Survey Open File Report 87-263.

END_XRD_ANALYSIS.

COMPOSITIONAL_ANALYSIS_TYPE: EM # XRF, EM(WDS), ICP(Trace), WChem


COMPOSITION
KEYWORD
Oxide
ASCII
Amount Weight
Percent, %
Oxide
html
COMPOSITION: SiO2 37.19 wt% SiO2
COMPOSITION: TiO2 0.03 wt% TiO2
COMPOSITION: Al2O3 63.62 wt% Al2O3
COMPOSITION: FeO 0.26 wt% FeO
COMPOSITION: MnO 0.01 wt% MnO
COMPOSITION: MgO 0.06 wt% MgO
COMPOSITION: CaO 0.02 wt% CaO
COMPOSITION: Na2O 0.02 wt% Na2O
COMPOSITION: K2O 0.01 wt% K2O
COMPOSITION: Total 101.22 wt%
COMPOSITION: O=Cl,F,S wt% #correction for Cl, F, S
COMPOSITION: New Total wt%

COMPOSITION_TRACE: None

COMPOSITION_DISCUSSION:

"Microprobe analysis shows the sample to be homogeneous within and between grains. Average of 10 analyses, indicating close to end member composition."

Salisbury, J. W., Walter, L. W., and Vergo, N., 1987, Mid-Infrared (2.1-25µm) Spectra of Minerals: First Edition, U.S. Geological Survey Open File Report 87-263.

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

avg. grain size = 245µm

Mixed pink & clear grains, mostly conchoidal fracture, some cleavage planes, length fast, high relief, moderate 2V, biaxial (-), pink pleochroism. All this is consistent with andalusite. 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 345 0.2-3.0µm 200 g.s.=
LIB_SPECTRA: splib05a r 949 0.2-3.0µm 200 g.s.=


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