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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: Geothite MPCMA2-B DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: MPCMA2-B

MINERAL_TYPE: Hydroxide

MINERAL: Goethite

FORMULA: alpha-FeO(OH)

FORMULA_HTML: alpha-FeO(OH)

COLLECTION_LOCALITY: Coliseum mine area, Mountain Pass, California, USA

ORIGINAL_DONOR: Roger Clark

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

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

SAMPLE_DESCRIPTION:

Fine grained rock coating. Visual estimate of grain size.

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

Muscovite-2M1(minor), calcite(trace), quartz(minor), microcline(minor), albite(minor). **Some goethites are XRD amorphous and lack of goethite detection in this case may mean that this sample is also XRD amorphous (see:Swayze, G.A., K.S. Smith, R.N. Clark, S.J., Sutley, R.M. Pearson, J.S. Vance, P.L. Hageman, P.H. Briggs, A.L. Meier, M.J. Singleton, and S. Roth, Using imaging spectroscopy to map acidic mine waste, Environmental Science and Technology, 34, 47-54, 2000).

END_XRD_ANALYSIS.

COMPOSITIONAL_ANALYSIS_TYPE: #XRF, EM(WDS), ICP(Trace),WChem

COMPOSITION_TRACE: None

COMPOSITION_DISCUSSION:

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

Spectral absorptions at 0.501, 0.666, and 0.9538 microns are all characteristic of goethite. None of the goethite Fe-absorptions are saturated probably because of the fine grained nature of the goethite coating. Bands around 1.4 and 2.2 microns are due to underlying muscovite in the host rock.

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 2850 0.2-3.0µm 200 g.s.=


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