Sample Description USGS Spectral Library Version 7

USGS Spectral Library Version 7 Sample Description

Kokaly, R.F., Clark, R.N., Swayze, G.A., Livo, K.E., Hoefen, T.M., Pearson, N.C., Wise, R.A., Benzel, W.M., Lowers, H.A., Driscoll, R.L., and Klein, A.J., 2017, USGS Spectral Library Version 7: U.S. Geological Survey Data Series 1035, 61 p., https://doi.org/10.3133/ds1035
_{For more information on the library, see:
local link
web link}

TITLE: Pigeonite HS199 DESCRIPT

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

IMAGE_OF_SAMPLE:

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 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