MINERAL: Hematite (Hematite group)
COLLECTION_LOCALITY: Ironton, MN
ORIGINAL_DONOR: Hunt and Salisbury Collection
CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory
ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory
Dimorphous with Maghemite.
The spectrum of this sample was originally published in:
Hunt, G.R., J.W. Salisbury, and C.J. Lenhoff, 1971, Visible and near-infrared spectra of minerals and rocks: III. Oxides and hydroxides. Modern Geology, v. 2, p. 195-205.
With the note that "this sample departs considerably from a pure stoichiometric single crystal, but is typical of naturally occurring hematite."
The sample measured for the library was HS45.3 which was dry sieved to the grain size interval 74-250µm. Compared to .3B samples, a grinding process was used which resulted in trace metal shavings from grinder.
40 kV - 30 mA, 7.3-9.5 keV
File: hemat45.mdi, *.out (smear mount on quartz plate)
References: Huebner's reference patterns
Found: Hematite; traces of quartz and a 7 Angstrom phase
Comment: Strong, narrow, symmetric hematite reflections indicate excellent crystallinity and suggest compositional heterogeneity. Hematite peak positions are consistent with Fe2O3 composition. The quartz identification is based upon two very weak (and broad) reflections. Very weak reflections at 7.2 and 3.55 Angstroms indicate the presence of a 7 or 14 Angstroms phase (possibly chlorite).
J.S. Huebner, J. Pickrell, and T. Schaefer, written communication 1994
COMPOSITIONAL_ANALYSIS_TYPE: None # XRF, EPMA, ICP(Trace), WChem
SPECTRAL_PURITY: 1b2b3c4u # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns