DOCUMENTATION_FORMAT: MINERAL
SAMPLE_ID: HS199.1B, HS199.2B, HS199.3B, HS199.4B
MINERAL_TYPE: Inosilicate
MINERAL: Pigeonite (Pyroxene group)
FORMULA: (Mg,Fe+2,Ca)(Mg,Fe+2)Si2O6
FORMULA_HTML: (Mg,Fe+2,Ca)(Mg,Fe+2)Si2O6
COLLECTION_LOCALITY: Loudoun County, Virginia
ORIGINAL_DONOR: Hunt and Salisbury Collection
CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory
ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory
SAMPLE_DESCRIPTION:
I-6 Pigeonite 199B-Londoun Co., Va. (Mg, Fe2+, Ca) (Mg, Fe2+) (Si2O6): This mineral is common in igneous rocks of the extrusive volcanic type, particularly in andesites and dacites. Its spectrum is quite flat with a broad feature at 0.95µ, typical of six-fold coordinated ferrous iron.
Hunt, G.R., J.W. Salisbury, and C.J. Lenhoff, 1973, Visible and near-infrared spectra of minerals and rocks: VI. Additional silicates. Modern Geology, v. 4, p. 85-106.
Grain size fractions are indicated by the extension after the sample number:
.1B = <5 µm
.2B = <74 µm
.3B = 74-250 µm
.4B = 250-1200 µm
END_SAMPLE_DESCRIPTION.
XRD_ANALYSIS:
40 kV - 30 mA, 7.3-9.5 keV
File: pignt199.out, -.mdi (smear mount on quartz plate)
References: Borg and Smith (1969); Huebner's reference patterns.
Found: high albite, clinopyroxene, minor quartz, many weak
unidentified reflections, including a possible ilmenite (211)
Comment: Sharp reflections suggest good crystallinity and compositional heterogeneity. Quartz has some unusual relative intensities, perhaps because the amount present is insufficient to give a random distribution of grain (lattice) orientations. The clinopyroxene pattern is very similar to that obtained from a lunar augite-pigeonite intergrowth; in neither case there are two clinopyroxenes resolved in the powder pattern.
J.S. Huebner, J. Pickrell, T. Schaefer, written communication(USGS)
END_XRD_ANALYSIS.
COMPOSITIONAL_ANALYSIS_TYPE: EPMA # XRF, EPMA, ICP(Trace), WChem
COMPOSITION KEYWORD |
Oxide ASCII |
Amount | Weight Percent, % |
Oxide html |
---|---|---|---|---|
COMPOSITION: | FeO | 25.31 | wt% | FeO |
COMPOSITION: | MnO | 40.86 | wt% | MnO |
COMPOSITION: | CaO | 33.93 | wt% | CaO |
COMPOSITION: | Total | wt% | ||
COMPOSITION: | O=Cl,F,S | wt% | #correction for Cl, F, S | |
COMPOSITION: | New Total | wt% |
COMPOSITION_TRACE:
COMPOSITION_DISCUSSION:
END_COMPOSITION_DISCUSSION.
MICROSCOPIC_EXAMINATION:
END_MICROSCOPIC_EXAMINATION.
SPECTROSCOPIC_DISCUSSION:
Relatively sharp spectral absorptions from contaminant(s) become progressively stronger with increasing grain size of the pigeonite samples culminating in bands at 1.4, 2.2, and 2.35 microns. Because of these sharp features we rated the spectral purity as a "c". G. Swayze.
END_SPECTROSCOPIC_DISCUSSION.
SPECTRAL_PURITY: 1b2_3_4_ # HS199.1B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1c2_3_4_ # HS199.2B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1c2c3c4_ # HS199.3B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1d2_3_4_ # HS199.4B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns