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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: Biotite WS660 DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: WS660

MINERAL_TYPE: Phyllosilicate

MINERAL: Annite (Mica group)

FORMULA: K(Fe+2)3AlSi3O10(OH,F)2

FORMULA_HTML: KFe+23AlSi3O10(OH,F)2

COLLECTION_LOCALITY: Bancroft, Ontario, Canada

ORIGINAL_DONOR: Wards Scientific

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

The sample appears uniform dark green and the visible-NIR spectrum shows strong iron bands and a spectrum typical of pure biotite.

IMAGE_OF_SAMPLE:
NO PHOTO

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

Trioctahedral mica - major - probably a mixture of compositions. No other components.

Konnert, Judith and Marta Flohr, 1992, unpublished data, USGS Reston, VA.

40 kV - 30 mA, 7.3-9.5 keV
File: annit660.out, -.mdi (edge=random mount)
References: Huebner's reference patterns; JCPDS #42-1413, 33-1016
Found: trioctahedral mica, 3T or 1M polytype

Comment: Basal reflections are surprisingly weak, even considering the use of a random mount. Some peak broadening or splitting suggests compositional heterogeneity of zoning. The position of the (060) is consistent with Fe/(Mg+Fe+Mn) = 0.25 +/- 0.05 (phlogopite), but not annite or siderophyllite.

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: SiO2 39.526 wt% SiO2
COMPOSITION: TiO2 2.042 wt% TiO2
COMPOSITION: Al2O3 11.052 wt% Al2O3
COMPOSITION: FeO 16.995 wt% FeO
COMPOSITION: MnO 0.693 wt% MnO
COMPOSITION: MgO 14.456 wt% MgO
COMPOSITION: CaO 0.008 wt% CaO
COMPOSITION: Na2O 0.607 wt% Na2O
COMPOSITION: K2O 9.668 wt% K2O
COMPOSITION: Cl 0.052 wt% Cl
COMPOSITION: F 3.181 wt% F
COMPOSITION: Total 98.281 wt%
COMPOSITION: O=Cl,F,S wt% #correction for Cl, F, S
COMPOSITION: New Total wt%

COMPOSITION_TRACE: None

COMPOSITION_DISCUSSION:

None

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

Bimodal grain size distribution:

population 1 avg. grain size size = 300µm 80 vol%
population 2 avg. grain size size = 10µm 20 vol%

avg. grain size of populations = 270µm

Pure biotite with larger grains 80% coated by smaller grains. Micaceous flakes with avg. flake diameter = 20µm. Biaxial (-), larger 2V, slight pleochroism, single good basal cleavage. G. Swayze

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1b2c3c4u # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns