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(For further information on spectrsocopy, see:
http://speclab.cr.usgs.gov)
TITLE: Epidote HS328 DESCRIPT
DOCUMENTATION_FORMAT: MINERAL
SAMPLE_ID: HS328
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: Arizona
ORIGINAL_DONOR: Hunt and Salisbury Collection
CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory
ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory
SAMPLE_DESCRIPTION:
Forms series with Clinozoisite.
"S-3 Epidote 328B--Arizona. Ca2(Al,Fe)Al2O• OH(Si2O7)(SiO4): This metamorphic mineral is the iron-rich end member of the clinozoisite-epidote series. The features are those due to both ferrous and ferric iron at 0.41, 0.47, near 0.6 µ and 1.0 µ. Again, the hydroxyl features are unusual. The feature at 1.55 µ appears, and it is accompanied by a very weak feature at 1.4 µ (not discernible in reproduced spectrum). The two features near 1.85 µ and 1.9 µ, like those in zoisite, are apparent, as is a very intense feature at 2.35 µ with well defined side features."
Hunt, G.R., J.W. Salisbury, and C.J. Lenhoff, 1973, Visible and near-infrared spectra of minerals and rocks: VI. Additional silicates. Modern Geology, v. 4, p. 85-106.
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)
END_XRD_ANALYSIS.
COMPOSITIONAL_ANALYSIS_TYPE: None # XRF, EM(WDS), ICP(Trace), WChem
COMPOSITION_TRACE: None
None
COMPOSITION_DISCUSSION:
None
END_COMPOSITION_DISCUSSION.
MICROSCOPIC_EXAMINATION:
mode:
80 vol% epidote
15 vol% quartz
3 vol% plagioclase ?
2 vol% magnetite
average grain size= 250 µm
Epidote grains are highly fractured or polygranular, with quartz intergrowths on about 10% of epidote grains. Individual crystal grain size is about 50 µm or less because of polygranular and fractured nature. Determination of optical properties is difficult because of fractures and polygranular nature.
END_MICROSCOPIC_EXAMINATION.
SPECTROSCOPIC_DISCUSSION:
END_SPECTROSCOPIC_DISCUSSION.
SPECTRAL_PURITY: 1c2_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 1575 | 0.2-3.0µm | 200 | g.s.= 250 µm |
| LIB_SPECTRA: | splib05a r 2630 | 0.2-3.0µm | 200 | g.s.= |
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