Clark et. al. 2003 USGS Open File Report 03-395
Spectral Library splib05a Sample Description

(For further information on spectrsocopy, see: http://speclab.cr.usgs.gov)

TITLE: Chrysotile_Gneiss ML99-12A DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: ML99-12A

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:

Coarse 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.

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

XRD analysis by Jim Post indicates that the sample is one half orthochrysotile and one half clinochrysotile.

END_XRD_ANALYSIS.

COMPOSITIONAL_ANALYSIS_TYPE: NONE #XRF, EM(WDS), 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 Fe-absorptions are more saturated than in sample ML99-12C because of the coarser fiber size of this sample. Strong Fe-related absorptions in the visible create a reflectance peak at about 0.553 microns that is not as notable in the fine grained sample ML99-12C. 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

LIB_SPECTRA_HED:	where	Wave Range	Av_Rs_Pwr	Comment
LIB_SPECTRA:	splib05a r 1844	0.2-3.0µm	200	g.s.=

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