Andalusite NMNHR17898

Spectrum Details

Modality

NIR

Category

mineral

Material Type

Nesosilicate

Sample ID

NMNH17898

Collection Locality

St. Theresa, Espirito Santo, Brazil

Spectral Purity

1c2_3_4_ # NMNHR17898 # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns SPECTRAL_PURITY: 1_2c3b4_ # NMNHR17898

Composition / XRD

EM # XRF, EPMA, ICP(Trace), WChem

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 IMAGE_OF_SAMPLE:

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.

X Units

cm⁻¹

Y Units

Absorbance

Data Points

2,126