TITLE: Clinochlore GDS158 Chlorite DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: GDS158

MINERAL_TYPE: Phyllosilicate

MINERAL: Clinochlore (Sheridanite) (Chlorite group)

FORMULA: (Mg,Fe+2)5Al(Si3Al)O10(OH)8

FORMULA_HTML: (Mg,Fe+2)5Al(Si3Al)O10(OH)8

COLLECTION_LOCALITY: Flagstaff Hill, California

ORIGINAL_DONOR: Jim Post

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

This sample described in:

Post, J.L. and C.C. Plummer, 1972, The chlorite series of Flagstaff Hill area, California: A preliminary investigation. Clays and Clay Minerals, v.20, pp271-283.

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

45 kV - 35 mA, 6.5-9.5 keV, smear mount (sherd8.out); 40 kV - 30 mA, random mount (sherd8-2.out)
References: Bailey (1988, MSA Reviews 19; 1988 in Clays and Clay Minerals); Huebner's reference patterns
Found: Chlorite type IIbb. A broad, very weak reflection at 9.6 is probably due to a trace of mica. A weak reflection at 3.23 angstroms may be due to a trace of feldspar. A weak unidentified reflection at 2.357 angstroms. And a weak, unidentified reflection at 7.8 angstroms that also appeared in GDS157 (the "ripidolite").
Sought but not found: quartz

Comments: With chemical analysis, the chlorite is a clinochlore IIbb. Severe preferred orientation in smear mounts; fortunately, there was enough sample for a random mount. Sharp chlorite reflections indicate excellent crystallinity. With GDS157 ("ripidolite"), the best chlorite patterns I have ever seen."

J.S. Huebner, J. Pickrell, and T.Schaefer, 1994, written communication.

40 kV- 30 mA, 7.3-9.5 keV
File sherd158.out, -.mdi (edge/random mount)
References: Bailey (1988 in Clays and Clay Minerals, 36, 193-213); Huebner's reference patterns
Found: clinichlore type IIbb, trace rutile

Comment: Sharp reflections suggest excellent crystallinity and compositional homogeneity. Position of the (060) reflection indicates Mg/(Mg+Fe+Mn) = 0.85. Presence of rutile confirmed optically; rutile forms thin but very elongate needles in the chlorite flkes ("rutilated clinochlore").

END_XRD_ANALYSIS.

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


COMPOSITION: SiO2 27.5 wt% SiO2
COMPOSITION: TiO2 1.04 wt% TiO2
COMPOSITION: Al2O3 19.8 wt% Al2O3
COMPOSITION: Cr2O3 0.057 wt% Cr2O3
COMPOSITION: Fe2O3 14.1 wt% Fe2O3
COMPOSITION: NiO 0.074 wt% NiO
COMPOSITION: MnO 0.13 wt% MnO
COMPOSITION: MgO 24.7 wt% MgO
COMPOSITION: CaO 0.10 wt% CaO
COMPOSITION: Na2O 0.22 wt% Na2O
COMPOSITION: K2O 0.03 wt% K2O
COMPOSITION: P2O5 0.11 wt% P2O5
COMPOSITION: LOI 11.5 wt% LOI
COMPOSITION: Total 99.361 wt%
COMPOSITION: O=Cl,F,S wt% #correction for Cl, F, S
COMPOSITION: New Total wt%

J.S.Huebner, J. Pickrell, T. Schaefer, unpublished, written communication (1994)

COMPOSITION_TRACE: None

COMPOSITION_DISCUSSION:

None

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

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 1088 0.2-3.0µm 200 g.s.=

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

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