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: Chrysotile_Gneiss ML99-12C DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: ML99-12C

MINERAL_TYPE: Phyllosilicate

MINERAL: Chrysotile (Kaolinite-Serpentine Group)

FORMULA: Mg3Si2O5(OH)4

FORMULA_HTML: Mg₃Si₂O₅(OH)₄

COLLECTION_LOCALITY: California Asbestos Quarry near New Melones Reservoir, CA

ORIGINAL_DONOR: California Asbestos Corporation

CURRENT_SAMPLE_LOCATION: U.S.G.S. Denver Spectroscopy Laboratory.

ULTIMATE_SAMPLE_LOCATION: U.S.G.S. Denver Spectroscopy Laboratory.

SAMPLE_DESCRIPTION:

Fine fiber Chrysotile

Sample from the California Asbestos Quarry located 1 km west of the New Melones Reservoir and 16 km west of Sonora, California in the foothills of the Sierra Nevada. Sample was collected from the NE pit wall in Dec. of 1999. Sample is from a vein of fibrous chrysotile sandwiched between massive antigorite wall rock. Sample used for spectral and XRD analysis was hand picked.

IMAGE_OF_SAMPLE:
NO PHOTO

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

XRD done by Jim Post indicates sample is chrysotile with considerable magnetite intermixed.

END_XRD_ANALYSIS.

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

COMPOSITION_TRACE: None

COMPOSITION_DISCUSSION:

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

Spectrum is typical of chrysotile with strong Fe-absorptions in the 0.5- 1.3 micron region and sharp vibrational features at 1.389, 2.126, and 2.3255 microns. The 1.389 micron absorption is the 1st overtone of the OH stretch while the 2.3255 micron absorption is the Mg-OH combination band. There is no spectral evidence of the magnetite which probably just lowers the overall reflectance of the sample.

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1b2_3_4_ # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns