TITLE: Diopside NMNHR18685 DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: NMNHR18685

MINERAL_TYPE: Inosilicate

MINERAL: Diopside (Pyroxene group)

FORMULA: CaMgSi2O6

FORMULA_HTML: CaMgSi2O6

COLLECTION_LOCALITY: DeKalb, New York

ORIGINAL_DONOR: Smithsonian

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

Forms series with Hedenbergite and with Johannsenite.

"Results of petrographic examination: Most of the sample, which is green and about 13mm x 10mm x 6mm is clean, fresh. There is one area which is eroded and weathered and probably impure. Crushed sample was hand-picked to avoid impurities. There is a moderate amount of weathering and alteration. Alteration is brown in color (limonite?)."

Salisbury, J. W., Walter, L. W., and Vergo, N., 1987, Mid-Infrared (2.1-25µm) Spectra of Minerals: First Edition, U.S. Geological Survey Open File Report 87-263.

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

Diopside plus a trace of quartz. Spectra show no quartz bands, but do show a trace of carbonate in reflectance of 74-250µ and 0-74µ size ranges.

Salisbury, J. W., Walter, L. W., and Vergo, N., 1987, Mid-Infrared (2.1-25µm) Spectra of Minerals: First Edition, U.S. Geological Survey Open File Report 87-263.

Diopside + tr. quartz (Norma Vergo).

END_XRD_ANALYSIS.

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


COMPOSITION: SiO2 54.77 wt% SiO2
COMPOSITION: TiO2 0.05 wt% TiO2
COMPOSITION: Al2O3 0.49 wt% Al2O3
COMPOSITION: FeO 0.87 wt% FeO
COMPOSITION: MnO 0.06 wt% MnO
COMPOSITION: MgO 18.26 wt% MgO
COMPOSITION: CaO 25.60 wt% CaO
COMPOSITION: Na2O 0.39 wt% Na2O
COMPOSITION: K2O 0.01 wt% K2O
COMPOSITION: Total 100.49 wt%
COMPOSITION: O=Cl,F,S wt% #correction for Cl, F, S
COMPOSITION: New Total wt%

COMPOSITION_TRACE: None

COMPOSITION_DISCUSSION:

Microprobe analysis showed sample to be homogeneous within and between grains examined. Average of 12 analyses indicates that this sample is close to end member composition.

Salisbury, J. W., Walter, L. W., and Vergo, N., 1987, Mid-Infrared (2.1-25µm) Spectra of Minerals: First Edition, U.S. Geological Survey Open File Report 87-263.

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

Mode:

95 vol% diopside
5 vol% quartz

grain sz fraction 74-250 µm: avg gr sz = 263 µm
grain sz fraction <74 µm: avg gr sz = 32 µm

Two cleavages at nearly right angles, inclined extinction. No optical evidence of calcite and no HCl acid fizz in either grain size fraction. G. Swayze.

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 1440 0.2-3.0µm 200 g.s.= 263 µm

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

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