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Clark et. al. 2003 USGS Open File Report 03-395
Spectral Library splib05a Sample Description

(For further information on spectrsocopy, see: http://speclab.cr.usgs.gov)

TITLE: Epidote GDS26 DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: GDS26

MINERAL_TYPE: Sorosilicate

MINERAL: Epidote (Epidote group)

FORMULA: Ca2(Al,Fe+3)3(SiO4)3(OH)

FORMULA_HTML: Ca2(Al,Fe+3)3(SiO4)3(OH)

COLLECTION_LOCALITY: Prince of Wales Island, Alaska

ORIGINAL_DONOR: Bruce Hemingway

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

Forms series with Clinozoisite.

"Results of petrographic examination: Deep green colored epidote crystals 2 cm x 1 cm in size. Looks pure. Microscopic examination indicates pure clean epidote with no alteration."

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.

Sample is in two sieve intervals: (a) 75-200µm and (b) less than 75µm.

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

Spectrally pure. Epidote plus a large amount of quartz plus a small amount other; M: ~2% magnetite on epidote, ~15% quartz, ~3% plagioclase, no carbonate. (Norma Vergo)

"Epidote plus a trace of quartz. No quartz bands are apparent in the spectrum; however, spectral features due to trace of a carbonate were seen and the sample was given acid treatment to remove this contaminant."

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


COMPOSITION
KEYWORD
Oxide
ASCII
Amount Weight
Percent, %
Oxide
html
COMPOSITION: SiO2 37.14 wt% SiO2
COMPOSITION: TiO2 0.16 wt% TiO2
COMPOSITION: Al2O3 23.05 wt% Al2O3
COMPOSITION: FeO 14.5 wt% FeO
COMPOSITION: MnO 0.18 wt% MnO
COMPOSITION: MgO 0.06 wt% MgO
COMPOSITION: CaO 22.85 wt% CaO
COMPOSITION: Na2O 0.01 wt% Na2O
COMPOSITION: K2O 0.02 wt% K2O
COMPOSITION: Total 97.97 wt%
COMPOSITION: O=Cl,F,S wt% #correction for Cl, F, S
COMPOSITION: New Total wt%

COMPOSITION_TRACE: None

COMPOSITION_DISCUSSION:

Microprobe analysis indicates that the sample is homogeneous within and between grains, and has typical epidote composition.

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:

75 < x < 200 µm fraction:
mode:
94 vol% epidote
5 vol% quartz
1 vol% plagioclase

average gr sz = 171 µm

Green pleochroism, pistachio green color, perfect cleavage, biaxial (-), high relief, all consistent with epidote.

< 75 µm fraction:
mode:
50 vol% epidote
50 vol% quartz (uniaxial (+), low order gray)

Bimodal gr sz distribution:
population 1 50 µm 40 vol%
population 2 7 µm 60 vol%

average grain size for entire population = 32 µm

Note: < 75 µm fraction significantly contaminated with quartz. G. Swayze.

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1b2_3_4_ # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns

LIB_SPECTRA_HED: where Wave Range Av_Rs_Pwr Comment
LIB_SPECTRA: splib04a r 1552 0.2-3.0µm 200 g.s.= 171 µm
LIB_SPECTRA: splib04a r 1564 0.2-3.0µm 200 g.s.= 32 µm
LIB_SPECTRA: splib05a r 2584 0.2-3.0µm 200 g.s.= 171 µm
LIB_SPECTRA: splib05a r 2598 0.2-3.0µm 200 g.s.= 32 µm


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