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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: Augite WS588 Pyroxene DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: WS558

MINERAL_TYPE: Inosilicate

MINERAL: Augite (Pyroxene Group, was listed as Diopside)

FORMULA: (Ca,Na)(Mg,Fe,Al,Ti)(Si,Al)2O6

FORMULA_HTML: (Ca,Na)(Mg,Fe,Al,Ti)(Si,Al)2O6

COLLECTION_LOCALITY: Hull, Ontario, Canada

ORIGINAL_DONOR: Wards Mineral Collection

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

IMAGE_OF_SAMPLE:
Photo of sample

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

40 kV - 30 mA, 6.7-9.5 keV
File: dipsd588_mdi (smear on qtz plate)
References: Borg and Smith (1969); PDF2 #41-1370, 24-0201; Huebner's reference patterns and cell refinements, particularly that of diopside from Rotkopschart, Zillertal, Austria
Found: Clinopyroxene

Comments: Peaks are moderately sharp to sharp but the alpha1-alpha2 components are not well resolved. The high background is probably due to X-ray fluorescence (suggesting (Fe and/or Mn are present). All reflections can be indexed as clinopyroxene.
Identification was confirmed with profile-based search-match (ferroan augite, 24-0201). Lattice spacing's are larger than those of WS-592, HS-15, or synthetic end member diopside, yet smaller than those of hedenbergite HS-10. Conclude that this material is a clinopyroxene solid solution, not an end member diopside.

END_XRD_ANALYSIS.

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

COMPOSITION_TRACE: None

COMPOSITION_DISCUSSION:

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

Bimodal grain size distribution:
population 1 grain size = 450 microns at 80 vol%
population 2 grain size = 15 microns at 20 vol%

avg. grain size = 400 microns

Pure sample, inclined extinction, two cleavages at nearly right angles, pale green color, high order colors under cross-polarized light, biaxial (+), weak pleochroism, all consistent with augite. G. Swayze.

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1b2c3b4b # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns