TITLE: Hypersthene PYX02 Pyroxene DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: PYX02

MINERAL_TYPE: Inosilicate

MINERAL: Hypersthene (Pyroxene group)

FORMULA: (Mg,Fe+2)2Si2O6 (En86)

FORMULA_HTML: (Mg,Fe+2)2Si2O6 (En86)

COLLECTION_LOCALITY: Bamble, Norway

ORIGINAL_DONOR: Wards Scientific, and Robert B. Singer

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

Intermediate member of the series Enstatite-Orthoferrosilite.

The original sample description and vis-nir spectrum was published by:

Singer, R.B., 1981, Near-Infrared spectral reflectance of mineral mixtures: Systematic combinations of pyroxenes, olivine, and iron oxides: J. Geophys Res., v. 86, p. 7967-7982.

The sample is pure pyroxene except for a small (<2%?) amount of tremolite. The tremoilte shows in the spectra as weak (narrow) bands at 2.3 µm and 1.4 µm. Singer suspected the tremolite, but it is confirmed by higher resolution spectra in this library.

The sample was ground and wet sieved in methanol at the USGS Denver Spectroscopy Laboratory by Roger Clark. Sieve intervals are:

5-10 µm (g)
10-20 µm (a)
20-30 µm (d)
30-45 µm (e)
45-104 µm (f)
104-150 µm (b)
150-250 µm (c)
>250 µm (h)

SEM photos were done by R. Clark on each sieve interval to characterize the grain sizes.

Letter denotes spectrum designation.

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

None

END_XRD_ANALYSIS.

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


COMPOSITION: SiO2 55.30 wt% SiO2
COMPOSITION: TiO2 0.05 wt% TiO2
COMPOSITION: Al2O3 0.12 wt% Al2O3
COMPOSITION: Fe2O3 (as FeO)wt% Fe2O3
COMPOSITION: FeO 9.38 wt% FeO
COMPOSITION: MnO 0.15 wt% MnO
COMPOSITION: MgO 32.80 wt% MgO
COMPOSITION: Na2O 0.00 wt% Na2O
COMPOSITION: P2O5 0.01 wt% P2O5
COMPOSITION: LOI 2.00 wt% LOI
COMPOSITION: Total 100.28 wt%
COMPOSITION: O=Cl,F,S wt% #correction for Cl, F, S
COMPOSITION: New Total 100.28 wt%

COMPOSITION_TRACE:

COMPOSITION_DISCUSSION:

The compositional analysis is from:
Singer, R.B., 1981, Near-Infrared spectral reflectance of mineral mixtures: Systematic combinations of pyroxenes, olivine, and iron oxides: J. Geophys Res., v. 86, p. 7967-7982.

All Fe2O3 is reported in the FeO amount. The analysis was performed by XRA Laboratory, Ontario Canada. FeO was by wet chemistry, all else by XRF.

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

The sample appears to be pure pyroxene except for a small (<~ 2%) amount of tremolite.

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 2263 0.2-3.0µm 200 g.s.=350 µm
LIB_SPECTRA: splib04a r 2274 0.2-3.0µm 200 g.s.=180 µm
LIB_SPECTRA: splib04a r 2285 0.2-3.0µm 200 g.s.=120 µm
LIB_SPECTRA: splib04a r 2296 0.2-3.0µm 200 g.s.=60 µm
LIB_SPECTRA: splib04a r 2308 0.2-3.0µm 200 g.s.=34 µm
LIB_SPECTRA: splib04a r 2319 0.2-3.0µm 200 g.s.=23 µm
LIB_SPECTRA: splib04a r 2330 0.2-3.0µm 200 g.s.=12 µm
LIB_SPECTRA: splib04a r 2341 0.2-3.0µm 200 g.s.= 7 µm

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

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