DOCUMENTATION_FORMAT: MIXTURE
SAMPLE_ID: GDS27
MIXTURE_TYPE: Coating
MIXTURE: Hematite
FORMULA: alpha-Fe2O3
FORMULA_HTML: alpha-Fe2O3
COLLECTION_LOCALITY: Chemical Reagent purchased from vendor.
ORIGINAL_DONOR: sample prepared by Gregg Swayze
COLLECTION_LATITUDE: Not Available # degrees and decimal minutes (N or S)
COLLECTION_LONGITUDE: Not Available # degrees and decimal minutes (W or E)
DATUM: Not Available # coordinate datum
CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory
ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory
SAMPLE_DESCRIPTION:
Sample was prepared from a chemical reagent of Fe2O3. Fine grained powder was mixed with water and an eye-dropper was used to deposit a thin coating on a microscope glass thin section. The sample was dried over night and them measured spectrally. Our goal was to unsaturate the goethite bands and mimic the spectral absorptions found in natural goethite coatings.
END_SAMPLE_DESCRIPTION.
XRD_ANALYSIS:
Pure Hematite (See Hematite GDS27)
END_XRD_ANALYSIS.
COMPOSITIONAL_ANALYSIS_TYPE: None # XRF, EPMA, ICP(Trace), WChem
COMPOSITION_TRACE: None
COMPOSITION_DISCUSSION:
None
END_COMPOSITION_DISCUSSION.
MICROSCOPIC_EXAMINATION:
END_MICROSCOPIC_EXAMINATION.
For hematite powder:
average grain size = 200 microns (aggregates) Material opaque, but hematite red in
powdered form. No impurities observed. Large 50-150 micron grain aggregates are
composed of 2-3 micron grains. G. Swayze.
SPECTROSCOPIC_DISCUSSION:
Spectrum has Fe-related absorptions characteristic of hematite. Bands are located at 0.5427, 0.6615, and 0.8675 microns. Of note is the narrow width of the 0.8675 micron band: it is only 157 nm wide -- much narrower than in spectra of powdered hematite samples. Apparently the band narrows most on the long wavelength side of this band in coatings.
END_SPECTROSCOPIC_DISCUSSION.
SPECTRAL_PURITY: 1a2_3_4_ # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns