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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.
IMAGE_OF_SAMPLE:
NO PHOTO
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, EPMA, 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