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DOCUMENTATION_FORMAT: MINERAL
SAMPLE_ID: WS222 Medium Gr., WS222 Coarse Gr.
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.
IMAGE_OF_SAMPLE:
NO PHOTO
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Konnert, Judith and Marta Flohr, 1992, unpublished data, USGS Reston, VA.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, EPMA, 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: 1a2a3a4u # Goethite WS222 Medium Gr. # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1a2_3_4_ # Goethite WS222 Coarse Gr. # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns