DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: HS346

MINERAL_TYPE: Cyclosilicate

MINERAL: Cordierite

FORMULA: Mg2Al4Si5O18

FORMULA_HTML: Mg₂Al₄Si₅O₁₈

COLLECTION_LOCALITY: Guffy, Colorado

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 Sekaninaite. Dimorphous with Indialite.

"C-2 Cordierite 346B--Guffy, Colo. Al₃(Mg, Fe²⁺)₂ (Si₅Al0₁₈): Cordierite is a mineral of metamorphic origin usually found in gneisses and crystalline schists, or in contact metamorphic zones. Its spectrum shows a weak Fe²⁺ feature at 0.95 µ, which is in accord with typical cordierite composition, and weak broad hydroxyl and water features at 1.4, 1.9, and 2.2 µ which are not. These latter bands are due to alteration products, principally muscovite. Reflectivities I through IV are 50%, 43%, 31%, and 12% at 1.0 µ."

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:

Cordierite + quartz + muscovite + talc (Norma Vergo)

END_XRD_ANALYSIS.

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

COMPOSITION_TRACE: None

COMPOSITION_DISCUSSION:

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

mode:
52-62 vol% cordierite
30-40 vol% mica (clear)
8 vol% opaques as inclusions in cordierite

Because of significant mica contamination, I suggest this sample be deleted from database. G. Swayze.

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 1260 0.2-3.0µm 200

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

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