Sample Description USGS Spectral Library Version 7

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
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TITLE: Adularia GDS57 Orthoclase DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: GDS57

MINERAL_TYPE: Tectosilicate

MINERAL: Adularia (Orthoclase, Feldspar group)

FORMULA: KAlSi3O8

FORMULA_HTML: KAlSi₃O₈

COLLECTION_LOCALITY: Floestenthal Tyrol, Austria

ORIGINAL_DONOR: Colorado School of Mines

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

K-feldspar commonly found in psuedo-orthorhombic crystals. It occurs mainly in low-temperature veins in gneisses and schists.

IMAGE_OF_SAMPLE:
NO PHOTO

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

Feldspar of orthoclase subgroup.

Konnert, Judith and Marta Flohr, 1992, unpublished data, USGS Reston, VA.

END_XRD_ANALYSIS.

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

COMPOSITION_TRACE: None

COMPOSITION_DISCUSSION:

None

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

Bimodal grain size distribution:

population 1 = 650µm 99 vol%
population 2 = 40µm 1 vol%

avg. grain size of populations = 648µm

Smaller grains cover 20% of larger tabular grains. Grains have low relief, first order gray interference color, no visible twins, refractive index close to 1.51 oil. This sample was ground from a single k-feldspar crystal. G. Swayze

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1b2b3b4b # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns