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: Olivine HS285 Fo80 DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: HS285.2B, HS285.4B

MINERAL_TYPE: Nesosilicate

MINERAL: Olivine (Olivine group)

FORMULA: Mg2SiO4-Fe2SiO4 Fo80

FORMULA_HTML: Mg₂SiO₄-Fe₂SiO₄ Fo₈₀

COLLECTION_LOCALITY: Arizona

ORIGINAL_DONOR: Hunt and Salisbury Collection

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

A spectrum for this sample was published in: Hunt, G.R., J.W. Salisbury, and C.J. Lenhoff, 1973, Visible and near-infrared spectra of minerals and rocks: VI. Additional silicates. Modern Geology, v. 4, p. 85-106.

With the note that the sample is Peridot, and the following comment: "This is a gem quality olivine which is 80Fo-20Fa. It contains a small amount of spinel as well as displaying a trace of iron oxide stain. The ferric iron band at 0.64µm is prominent in the larger particle size sample."

For additional information on the spectra of olivine's see: King, T.V.V. and W.I. Ridley, 1987, Relation of the Spectroscopic Reflectance of Olivine to Mineral Chemistry and Some Remote Sensing Implications. J. Geophys. Res., 11,457-11,469.

Grain size fractions are indicated by the extension after the sample number:
.2B = <74 µm
.4B = 250-1200 µm

IMAGE_OF_SAMPLE:

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

40 kV - 30 mA, 7.0-9.5 keV
File: oliv285.mdi (smear on quartz plate)
References: PDF2 #34-0189
Found: Forsterite

Comments: Sharp peaks show good resolution of the alpha1-alpha2 components. Some peaks have slight shoulders toward larger d-spacings. PDF2 34-0189 (synthetic forsterite) is an excellent match for HS-285, much better than 31-0795 (ferroan forsterite). One very weak peak at 2.85 Angstroms has not been identified. The shoulders could be caused by slight Fe-Mg zoning.

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:

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1b2_3_4_ # HS285.2B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1b2b3b4_ # HS285.4B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns