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: Glaucophane HS426 DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: HS426

MINERAL_TYPE: Inosilicate

MINERAL: Glaucophane (Amphibole group)

FORMULA: Na2(Mg,Fe+2)3Al2Si8O22(OH)2

FORMULA_HTML: Na2(Mg,Fe+2)3Al2Si8O22(OH)2

COLLECTION_LOCALITY: California

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 Ferroglaucophane.

Original spectrum published in: 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.

With the comment:"The iron-free end member is very rare, and in most glaucophane there is some replacement of Mg by Fe2+ and of Al by Fe3+. Such substitution results in the broad absorption from 0.6 to 1.0µm. The 1.4µm hydroxyl band is quite evident, and the 2.32µm feature is the best resolved band in the spectrum. The 1.9µm band indicates that a little included water is present."

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

Analysis by Norma Vergo indicates glaucophane + chlorite + others.

END_XRD_ANALYSIS.

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

COMPOSITION_TRACE: None

COMPOSITION_DISCUSSION:

None.

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

Mineral Mode:
60 vol% glaucophane
25 vol% chlorite
12 vol% qtz or feldspar
3 vol% muscovite

average grain size of glauconite only = 284 µm

Glaucophane has light blue-purple pleochroism, amphibole cleavage, length slow, biaxial (-), small Z angle C, all consistent with glaucophane. I suggest cleaning up 4B and crushing hand picked grains. 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 1771 0.2-3.0µm 200 g.s.= 284 µm
LIB_SPECTRA: splib05a r 2828 0.2-3.0µm 200 g.s.=


USA.gov logo  Take Pride in America button