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 GDS70 Fo89 DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: GDS70.a, GDS70.b, GDS70.c, GDS70.d, GDS70.e

MINERAL_TYPE: Nesosilicate

MINERAL: Olivine (Olivine group)

FORMULA: Mg2SiO4-Fe2SiO4 Fo89

FORMULA_HTML: Mg₂Si₄-Fe₂SiO₄ Fo₈₉

COLLECTION_LOCALITY: South Point, Hawaii, Hawaii

ORIGINAL_DONOR: Roger N. Clark

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

This sample is commonly referred to as the "green sand beach" olivine. The sample was sieved into grain size fractions. All samples were examined using a petrographic microscope and hand-picked prior to wet-sieving.

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:
.e = less than 30µm
.d = less than 60µm
.c = 60-104µm with a median grain size of 70µm
.b = 104-150µm with a median grain size of 115µm
.a = 150-250µm with a median grain size of 165µm

IMAGE_OF_SAMPLE:
NO PHOTO

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

Forsterite plus possible trace corundum. (Steve Sutley)

END_XRD_ANALYSIS.

COMPOSITIONAL_ANALYSIS_TYPE: EPMA # XRF, EPMA, ICP(Trace), WChem

COMPOSITION
KEYWORD Oxide
ASCII Amount Weight
Percent, % Oxide
html

COMPOSITION: SiO2 41.09 wt% SiO₂

COMPOSITION: TiO2 0.01 wt% TiO₂

COMPOSITION: Cr2O3 0.05 wt% Cr₂O₃

COMPOSITION: FeO 9.16 wt% FeO

COMPOSITION: NiO 0.39 wt% NiO

COMPOSITION: MnO 0.21 wt% MnO

COMPOSITION: MgO 49.29 wt% MgO

COMPOSITION: CaO 0.03 wt% CaO

COMPOSITION: Total 100.23 wt%

COMPOSITION: O=Cl,F,S wt% #correction for Cl, F, S

COMPOSITION: New Total wt%

COMPOSITION KEYWORD	Oxide ASCII	Amount	Weight Percent, %	Oxide html
COMPOSITION:	SiO2	41.09	wt%	SiO₂
COMPOSITION:	TiO2	0.01	wt%	TiO₂
COMPOSITION:	Cr2O3	0.05	wt%	Cr₂O₃
COMPOSITION:	FeO	9.16	wt%	FeO
COMPOSITION:	NiO	0.39	wt%	NiO
COMPOSITION:	MnO	0.21	wt%	MnO
COMPOSITION:	MgO	49.29	wt%	MgO
COMPOSITION:	CaO	0.03	wt%	CaO
COMPOSITION:	Total	100.23	wt%
COMPOSITION:	O=Cl,F,S		wt%	#correction for Cl, F, S
COMPOSITION:	New Total		wt%

COMPOSITION_TRACE:

COMPOSITION_DISCUSSION:

Microprobe analysis by W.I. Ridley at the USGS microprobe facility in Denver, Colorado.

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

This appears to be a pure mineral separate through the microscope. Some spectra show weak 2.3 µm alteration features. The rest of the spectrum rates an "a" on the spectral purity scale. Because of the trace alteration, however, the spectra rate a "b" overall.

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION: There are notably deep C-H stretch absorptions around 3.4 microns in grain size series members "d" and "e", which lower the overall spectral purity rating in those regions. G. Swayze.

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1b2b3b4b # GDS70.a # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1b2b3b4b # GDS70.b # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1b2b3b4b # GDS70.c # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1b2c3b4b # GDS70.d # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1b2c3b4b # GDS70.e # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns