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USGS Spectral Library Version 7 Sample Description

Kokaly, R.F., Clark, R.N., Swayze, G.A., Livo, K.E., Hoefen, T.M., Pearson, N.C., Wise, R.A., Benzel, W.M., Lowers, H.A., Driscoll, R.L., and Klein, A.J., 2017, USGS Spectral Library Version 7: U.S. Geological Survey Data Series 1035, 61 p., https://doi.org/10.3133/ds1035
For more information on the library, see: local link web link

TITLE: Glaucophane HS426 DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: HS426.1B, HS426.2B, HS426.3B, HS426.4B, HS426.6

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."

Grain size fractions are indicated by the extension after the sample number:
.1B = <5 µm
.2B = <74 µm
.3B = 74-250 µm
.4B = 250-1200 µm
.6 = cut slab

IMAGE_OF_SAMPLE:
Photo of sample

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

Analysis by Norma Vergo indicates glaucophane + chlorite + others.

END_XRD_ANALYSIS.

COMPOSITIONAL_ANALYSIS_TYPE: None # XRF, EPMA, 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_ # Glaucophane HS426.1B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1c2_3_4_ # Glaucophane HS426.2B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1c2c3c4c # Glaucophane HS426.3B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1c2_3_4_ # Glaucophane HS426.4B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1c2_3_4_ # Glaucophane HS426.6 # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns