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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: Diopside HS317 (Cr)Pyx DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: HS317.1B, HS317.2B, HS317.3B, HS317.4B, HS317.6

MINERAL_TYPE: Inosilicate

MINERAL: Diopside (Pyroxene group)

FORMULA: CaMgSi2O6

FORMULA_HTML: CaMgSi2O6

COLLECTION_LOCALITY: Finland

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 Hedenbergite and with Johannsenite.

"This sample contains both ferrous and ferric iron which produce the absorptions at 0.45, 0.65 and 1.07µm. Ferrous iron substitutes for Mg in diopside. Cr also substitutes for Mg in this sample."

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.

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:

Primarily pyroxene; best matches are augite and diopside, but this is not definitive. Small amounts of other phases - pectolite, polyhalite, lazulite are possible contributors to residual.

Konnert, Judith and Marta Flohr, 1992, unpublished data, USGS Reston, VA.

Diopside is the major phase with trace amounts of hornblende, quartz, and clay (possibly talc or pyrophyllite). B. Benzel. 2016

END_XRD_ANALYSIS.

COMPOSITIONAL_ANALYSIS_TYPE: None # XRF, EPMA, ICP(Trace), WChem

COMPOSITION_TRACE: None

COMPOSITION_DISCUSSION:

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

mode:
94 vol% Diopside
5 vol% Calcite (estimated by fizz in HCl)
1 vol% magnetite (as inclusions in diopside grains)

Very pale green color, some diopside grains white, two cleavages at nearly right angles, inclined extinction, biaxial (+), consistent with diopside. G. Swayze.

Sharp absoprtions a 2.3, 3.5, and 4 microns may indicate the presence of talc or tremolite. G. Swayze

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1c2_3_4_ # Diopside HS317.1B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1c2_3_4_ # Diopside HS317.2B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1c2d3c4c # Diopside HS317.3B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1c2_3_4_ # Diopside HS317.4B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1c2_3_4_ # Diopside HS317.6 # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns