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) <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 contaminent."
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: | 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
avg 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 grey)
Bimodal gr sz distribution:
pop 1 50 µm 40 vol%
pop 2 7 µm 60 vol%
avg gr sz 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: 1_2_3_4_
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 ____ 0.2-3.0µm 200 g.s.=
LIB_SPECTRA: splib06a r ____ 1.5-25µm 250 g.s.=