TITLE: Annite WS661 Biotite 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: Faraday, 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 annite. The sample is darker than WS660 and the absorption features near 2.3-µm are weaker, possibly indicating a more iron rich end-member than WS660.

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Konnert, Judith and Marta Flohr, 1992, unpublished data, USGS Reston, VA.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: annit661.out, -.mdi (smear mount on quartz plate)
References: Huebner's reference patterns
Found: trioctahedral mica, 3T or 1M polytype, unindexed weak reflections at 8.8 and 4.24 angstroms

Comment: Non-basal reflections are surprisingly weak, even copnsidering the smear mount. Some peak broadening or splitting, as in WS-660. Based on the position of the (060) reflection, caould not distinguish between siderophyllite (60-100%) - annite solution or annite (70-90%) - phlogopite solution

J.S. Huebner, J. Pickrell, T. Schaefer, written communication(USGS)

END_XRD_ANALYSIS.

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


COMPOSITION: SiO2 33.489 wt% SiO2
COMPOSITION: TiO2 0.542 wt% TiO2
COMPOSITION: Al2O3 14.513 wt% Al2O3
COMPOSITION: FeO 33.840 wt% FeO
COMPOSITION: MnO 1.775 wt% MnO
COMPOSITION: MgO 0.006 wt% MgO
COMPOSITION: CaO 0.011 wt% CaO
COMPOSITION: Na2O 0.360 wt% Na2O
COMPOSITION: K2O 8.876 wt% K2O
COMPOSITION: Cl 0.196 wt% Cl
COMPOSITION: F 2.060 wt% F
COMPOSITION: Total 95.667 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 160µm 90 vol%
population 2 25µm 10 vol%

av gr sz of populations = 150µm

Pure sample, large grains 60% coated with smaller grains, slight pleochroism. 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 446 0.2-3.0µm 200 g.s.= 150 µm

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

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