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Clark et. al. 2003 USGS Open File Report 03-395
Spectral Library splib05a Sample Description

(For further information on spectrsocopy, see: http://speclab.cr.usgs.gov)

TITLE: Acmite NMNH133746 Pyroxene DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: NMNH133746

MINERAL_TYPE: Inosilicate

MINERAL: Acmite (Aegirine)(Pyroxene group)

FORMULA: NaFeSi2O6

FORMULA_HTML: NaFeSi2O6

COLLECTION_LOCALITY: Kangerdluarssuk, Narssaq (near), Greenland

ORIGINAL_DONOR: Smithsonian

CURRENT_SAMPLE_LOCATION: USGS Reston, VA

ULTIMATE_SAMPLE_LOCATION: USGS Reston, VA

SAMPLE_DESCRIPTION:

This sample was obtained by John W. Salisbury, and the original sample analysis and mid-infrared spectra were published in:

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.

"Original sample was large (up to 2cm), very dark green prismatic crystals of acmite intergrown with albite(?). Material was crushed and hand picked by J. Salisbury for grinding."

Sieve interval is: 74-250 µm

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

The 74-250 µm grains were x-rayed by Norma Vergo. The resulting pattern showed acmite and an unidentified peak of trace proportions at 4.48 angstroms.

see:

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_XRD_ANALYSIS.

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

COMPOSITION
KEYWORD
Oxide
ASCII
Amount Weight
Percent, %
Oxide
html
COMPOSITION: SiO2 52.08 wt% SiO2
COMPOSITION: TiO2 0.56 wt% TiO2
COMPOSITION: Al2O3 0.98 wt% Al2O3
COMPOSITION: FeO 29.22 wt% FeO
COMPOSITION: MnO 0.24 wt% MnO
COMPOSITION: MgO 0.06 wt% MgO
COMPOSITION: CaO 3.84 wt% CaO
COMPOSITION: Na2O 11.87 wt% Na2O
COMPOSITION: K2O 0.02 wt% K2O
COMPOSITION: Total 98.87 wt%
COMPOSITION: O=Cl,F,S wt%
COMPOSITION: New Total wt%

COMPOSITION_TRACE: None

COMPOSITION_DISCUSSION:

From: 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.

Microprobe analysis showed that one grain out of four examined had about 2 wt % more CaO and correspondingly less Na2O. Otherwise, homogeneous, especially within grains. Average of 13 analyses, which indicates close to end member composition.

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

avg. grain size = 265µm

Mostly clean cleavage surfaces of prismatic grains. Trace of quartz or plagioclase. Prismatic grains are length fast, have straight extinction, prismatic habit and yellow-green pleochroism, all consistent with Acmite. G. Swayze

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1a2_3_4_ # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns

LIB_SPECTRA_HED: where Wave Range Av_Rs_Pwr Comment
LIB_SPECTRA: splib04a r 16 0.2-3.0µm 200 g.s.=
LIB_SPECTRA: splib05a r 53 0.2-3.0µm 200 g.s.=


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