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(For further information on spectrsocopy, see:
http://speclab.cr.usgs.gov)
TITLE: Opalized Tuff CU00-15E DESCRIPT
DOCUMENTATION_FORMAT: MIXTURE
SAMPLE_ID: CU00-15E
MIXTURE_TYPE: Intimate
MIXTURE: Opal + others
FORMULA: SiO2*nH2O + others
FORMULA_HTML: SiO2*nH2O + others
COLLECTION_LOCALITY: Opal Hill, Eastern Altertion Center, Cuprite, Nevada, USA
ORIGINAL_DONOR: Gregg Swayze
COLLECTION_LATITUDE: N37 32.83' # degrees and decimal minutes (N or S)
COLLECTION_LONGITUDE: W117 10.02' # degrees and decimal minutes (W or E) P> DATUM: NAD27 # coordinate datum
CURRENT_SAMPLE_LOCATION: U.S.G.S. Denver Spectroscopy Laboratory
ULTIMATE_SAMPLE_LOCATION: U.S.G.S. Denver Spectroscopy Laboratory
SAMPLE_DESCRIPTION:
This sample was collected from a freshly exposed silica quarry on Opal Hill in the central portion of the eastern alteration center along its eastern margin. The sample was collected from an altered Tertiary Tuff that underwent hydrothermal alteration about 6.6 Ma.
END_SAMPLE_DESCRIPTION.
XRD_ANALYSIS:
Cristobalite and/or opal (major), quartz (major), calcite (minor), tridymite (trace).
END_XRD_ANALYSIS.
COMPOSITIONAL_ANALYSIS_TYPE: XRF # XRF, EM(WDS), ICP(Trace), WChem
COMPOSITION_TRACE: None
COMPOSITION_DISCUSSION:
None
END_COMPOSITION_DISCUSSION.
MICROSCOPIC_EXAMINATION:
None
END_MICROSCOPIC_EXAMINATION.
SPECTROSCOPIC_DISCUSSION:
The spectrum has absorptions characteristic of opal. In particular is the small shoulder at 1.4602 microns on the long wavelength side of the 1st OH stretch overtone at 1.4087 microns. This should appears in samples bearing cristobalite or opal. There is also a broad Si-OH combination band at 2.2165 microns that is a bit narrower than in chalcedony (e.g. compare with CU91-6A).
See: Swayze, G.A., 1997, The hydrothermal and structural history of the Cuprite Mining District, southwestern Nevada: an integrated geological and geophysical approach: unpublished Ph.D. Dissertation, University of Colorado at Boulder, 399p.
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: | splib05a r 8873 | 0.2-3.0µm | 200 | g.s.= |
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