DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: HS186

MINERAL_TYPE: Nesosilicate

MINERAL: Sillimanite

FORMULA: Al2SiO5

FORMULA_HTML: Al₂SiO₅

COLLECTION_LOCALITY: Australia

ORIGINAL_DONOR: Hunt and Salisbury Collection

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

"This comparatively rare mineral is found in high grade metamorphic rocks, particularly gneiss and schist. Its spectrum shows a rapid fall off in intensity to the blue, which is probably due to the trace of ferric ion replacing aluminum. This sample is slightly altered to montmorillonite, which accounts for the strong hydroxyl (1.4 and 2.2µm) and weaker water (1.9µm) bands. The 2.2µm feature is probably a combination of the OH stretch with the AlOH bend."

Hunt, G.R., J.W. Salisbury, and C.J. Lenhoff, 1973, Visible and near-infrared spectra of minerals and rocks: VI. Additional silicates. Modern Geology, v. 4, p. 85-106.

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

Sillimanite plus small amount of quartz, trace amount of pyrophyllite. (Norma Vergo)

END_XRD_ANALYSIS.

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

COMPOSITION_TRACE:

COMPOSITION_DISCUSSION:

No compositional analyses.

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1_2_3_4_

LIB_SPECTRA_HED: where Wave Range Av_Rs_Pwr Comment

LIB_SPECTRA: splib04a r 4467 0.2-3.0µm 200 g.s.=

LIB_SPECTRA: splib05a r ____ 0.2-3.0µm 200 g.s.=

LIB_SPECTRA: splib06a r ____ 1.5-25µm 250 g.s.=