Sample Description USGS Spectral Library Version 7

USGS Spectral Library Version 7 Sample Description

Kokaly, R.F., Clark, R.N., Swayze, G.A., Livo, K.E., Hoefen, T.M., Pearson, N.C., Wise, R.A., Benzel, W.M., Lowers, H.A., Driscoll, R.L., and Klein, A.J., 2017, USGS Spectral Library Version 7: U.S. Geological Survey Data Series 1035, 61 p., https://doi.org/10.3133/ds1035
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TITLE: Hematite HS45 DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: HS45.3

MINERAL_TYPE: Oxide

MINERAL: Hematite (Hematite group)

FORMULA: alpha-Fe2O3

FORMULA_HTML: alpha-Fe₂O₃

COLLECTION_LOCALITY: Ironton, MN

ORIGINAL_DONOR: Hunt and Salisbury Collection

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

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.

IMAGE_OF_SAMPLE:
NO PHOTO

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

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

END_XRD_ANALYSIS.

COMPOSITIONAL_ANALYSIS_TYPE: None # XRF, EPMA, ICP(Trace), WChem

COMPOSITION_TRACE:

COMPOSITION_DISCUSSION:

None.

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1b2b3c4u # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns