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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
For more information on the library, see: local link web link

TITLE: Lepidocrocite GDS80 (Syn) DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: GDS80

MINERAL_TYPE: Hydroxide

MINERAL: Lepidocrocite (Synthetic)

FORMULA: gamma-FeO(OH)

FORMULA_HTML: gamma-FeO(OH)

COLLECTION_LOCALITY: Synthetic, Dave Sherman

ORIGINAL_DONOR: Dave Sherman

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

Polymorphous with Akaganeite, Feroxyhyte, and Goethite.

"This sample was synthesized by aerial oxidation of a FeCl2 solution at a pH or 6-7. The X ray diffraction pattern of this sample was extremely well-defined, implying a high degree of crystallinity."

The above description may apply to this sample. This sample was one of a series of samples made for the following paper:

Sherman, D.M., R.G. Burns, and V.M. Burns, 1982, Spectral characteristics of the iron oxides with application to the Martian bright region mineralogy. Journal of Geophysical Research, v. 87, n. B12, pp. 10169- 10180.

IMAGE_OF_SAMPLE:
Photo of sample

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

40 kV - 30 mA, 7.3-9.5 keV
File: lepicr80.out, -.mdi
Reference: JCPDS #8-98, 29-713
Found: lepidocrocite and goethite in subequal proportions
Sought: quartz (see comment)

Comment: Poorly crystallized: weak, broad reflections for both oxides. The goethite (110) and lepidocrocite (120) reflections are in the positions of the quartz (100) and (101) reflections and would prevent X-ray powder detection of a small amount of quartz, if present.

J.S. Huebner, J. Pickrell, T. Schaefer, written communication 1994, Reston, VA.

END_XRD_ANALYSIS.

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

COMPOSITION_DISCUSSION:

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

Because the spectra of lepidocrocite is expected to resemble that of goethite it is unknown to what extent the goethite contaminant spectrally interferes with the lepidocrocite spectral features in this sample. G. Swayze

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1b2b3b4u # GDS80 # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns