TITLE: Antigorite NMNH17958 DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: NMNH17958

MINERAL_TYPE: Phyllosilicate

MINERAL: Antigorite (Kaolinite-Serpentine group)

FORMULA: (Mg,Fe+2)3Si2O5(OH)4

FORMULA_HTML: (Mg,Fe+2)3Si2O5(OH)4

COLLECTION_LOCALITY: Kalsertal, Tyrol, Austria

ORIGINAL_DONOR: Jim Crowley

CURRENT_SAMPLE_LOCATION: USGS Reston, VA

ULTIMATE_SAMPLE_LOCATION: Smithsonian

SAMPLE_DESCRIPTION:

Polymorphous with Clinochrysotile, Lizardite and Orthochyrsotile.

Large green single crystal.

Salisbury, J. W., Walter, L. W., and Vergo, N., 1987, Mid-Infrared (2.1-25µm) Spectra of Minerals: First Edition, U.S. Geological Survey Open File Report 87-263.

Specrally this sample is similar to other antigorites. King, T.V.V. and R.N. Clark, 1989, Spectral Characteristics of Chlorites and Mg-Serpentines Using high-Resolution Reflectance Spectroscopy. Jour. Geophys. Res., 13.997-14,008.

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

Pure magnesian antigorite.

Salisbury, J. W., Walter, L. W., and Vergo, N., 1987, Mid-Infrared (2.1-25µm) Spectra of Minerals: First Edition, U.S. Geological Survey Open File Report 87-263.

END_XRD_ANALYSIS.

COMPOSITIONAL_ANALYSIS_TYPE: None # XRF, EM(WDS), ICP(Trace), WChem

COMPOSITION_TRACE: None

COMPOSITION_DISCUSSION:

Pure magnesian serpentine.

Salisbury, J. W., Walter, L. W., and Vergo, N., 1987, Mid-Infrared (2.1-25µm) Spectra of Minerals: First Edition, U.S. Geological Survey Open File Report 87-263.

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

Under the microscope, appears mostly pure antigorite, but some (<3%) alteration or impurity, possibly chrysotile.

Salisbury, J. W., Walter, L. W., and Vergo, N., 1987, Mid-Infrared (2.1-25µm) Spectra of Minerals: First Edition, U.S. Geological Survey Open File Report 87-263.

Bimodal grain size distribution:

gr sz pop 1 : 300 µm at 40 vol%
gr sz pop 2 : 10 µm at 60 vol%

av gr sz = 110 µm

Pale green color, platy habit, 1st order gray, parallel extinction, prismatic habit in some grains (chrysotile?). 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 573 0.2-3.0µm 200 g.s.= 110 µm

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

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