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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: Goethite WS222 DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: WS222

MINERAL_TYPE: Hydroxide

MINERAL: Goethite

FORMULA: alpha-FeO(OH)

FORMULA_HTML: alpha-FeO(OH)

COLLECTION_LOCALITY: Superior Mine, Marquette, Michigan

ORIGINAL_DONOR: Wards Natural Science Inc.

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

Sample hand ground from botryoidal sample. Impurities were removed prior to grinding. Polymorphous with Akaganeite, Feroxyhyte, and Lepidocrocite.

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

Goethite
Perhaps some quartz

Konnert, Judith and Marta Flohr, 1992, unpublished data, USGS Reston, VA.

END_XRD_ANALYSIS.

COMPOSITIONAL_ANALYSIS_TYPE: None # XRF, EM(WDS), ICP(Trace), WChem

COMPOSITION_TRACE: None

COMPOSITION_DISCUSSION:

None.

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

Bimodal grain size distribution:
mode 1: average grain size= 227 µm @ 30 vol%
mode 2: average grain size= 5 µm @ 70 vol%

average grain size= 125 µm

No visible impurities; large fibrous grains are 90% coated with finer grains. High relief, moderate red pleochroism, prismatic cleavage. All this is consistent with pure goethite. G. Swayze.

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1a2_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: splib04a r 1781 0.2-3.0µm 200 g.s.= 125 µm
LIB_SPECTRA: splib05a r 2903 0.2-3.0µm 200 g.s.=
LIB_SPECTRA: splib05a r 2915 0.2-3.0µm 200 g.s.=


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