TITLE: Olivine GDS71 Fo91 DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: GDS71

MINERAL_TYPE: Nesosilicate

MINERAL: Olivine

FORMULA: Mg2SiO4-Fe2SiO4

FORMULA_HTML: Mg2Si4-Fe2SiO4 Fo91

COLLECTION_LOCALITY: Twin Sisters Peak, Washington

ORIGINAL_DONOR: Trude V.V. King

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

Samples were wet-sieved into <60µm (b) and 60-104µm (a) size fractions and hand-picked prior to spectral measurements. This sample was derived from a dunite.

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.

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

40 kV - 30 mA, 7.3-9.5 keV
File: oliv71.mdi (smear on qtz plate)
References: PDF2 #34-0189, 31-0795
Found: Forsterite

Comments: Sharp peaks show good resolution of the alpha1-alpha2 components. The pattern is very similar to that of HS-285.4B, including the shoulders. PDF2 34-0189 (synthetic endmember forsterite) is an excellent match for GDS-71, much better than 31-0795 (ferroan forsterite). The shoulders could be caused by slight Fe-Mg zoning.

END_XRD_ANALYSIS.

COMPOSITIONAL_ANALYSIS_TYPE: EM(WDS) # XRF, EM(WDS), ICP(Trace), WChem

COMPOSITION: SiO2 40.06 wt% SiO2
COMPOSITION: TiO2 0.14 wt% TiO2
COMPOSITION: Cr2O3 0.06 wt% Cr2O3
COMPOSITION: FeO 7.93 wt% FeO
COMPOSITION: NiO 0.28 wt% NiO
COMPOSITION: MnO 0.12 wt% MnO
COMPOSITION: MgO 50.70 wt% MgO
COMPOSITION: CaO 0.06 wt% CaO
COMPOSITION: Total 99.94 wt%

COMPOSITION_TRACE:

COMPOSITION_DISCUSSION:

This is a USGS microprobe standard analysis of Twin Sister Peak, Washington, dunite.

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.

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

This is a pure mineral separate. There are weak 2.3-µm alteration features, The rest of the spectrum rates an a.

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1_2_3_4_

LIB_SPECTRA_HED: where Wave Range Av_Rs_Pwr Comment

LIB_SPECTRA: splib04a r 3724 0.2-3.0µm 200 g.s.=65µm
LIB_SPECTRA: splib04a r 3735 0.2-3.0µm 200 g.s.=30µm

LIB_SPECTRA: splib05a r ____ 0.2-3.0µm 200 g.s.=

LIB_SPECTRA: splib06a r ____ 1.5-25µm 250 g.s.=