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(For further information on spectrsocopy, see:
http://speclab.cr.usgs.gov)
TITLE: Chabazite+Thomsonite+Wairaikite HS193 DESCRIPT
DOCUMENTATION_FORMAT: Mixture
SAMPLE_ID: HS193
MIXTURE_TYPE: Intimate
MIXTURE: Chabazite+Thomsonite+Wairaikite (Zeolite group)
FORMULA: CaAl2Si4012*6H2O + NaCa2Al5Si5O20*6H2O + CaAl2Si4O12*2H2O
FORMULA_HTML: CaAl2Si4012•6H2O + NaCa2Al5Si5O20•6H2O + CaAl2Si4O12•2H2O
COLLECTION_LOCALITY: Colorado
ORIGINAL_DONOR: Hunt and Salisbury Collection
CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory
ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory
SAMPLE_DESCRIPTION:
Chabazite is usually found in rhombohedral crystals, with nearly cubic angles. The ideal composition listed in the FORMULA field often has considerable replacement of Ca by Na and K as well as (Na,K)Si for CaAl. The structure of chabazite consists of an Al-Si-O framework with large cage like openings bounded by rings of tetrahedra. The cages are connected to each other by channels which allow diffusion of molecules of less than ~3.9 Angstroms.
The bands seen in its near-infrared spectrum are typical of large quantities of molecular water.
See: Hunt, G.R., J.W. Salisbury, 1970, Visible and near-infrared spectra of minerals and rocks: I. Silicate minerals. Modern Geology, v. 1, p. 283-300.
END_SAMPLE_DESCRIPTION.
XRD_ANALYSIS:
40 kV - 30 mA, 6.5-9.5 keV
File: chab193.out, -.mdi; chabz193.out, -.mdi
References: JCPDS # 34-137, 35-498, 42-1451
Found: Chabazite, thomasite (thomsonite?), wairaikite in sub equal proportions
Comment: Reflections are sharp and strong, suggesting good crystallinity and compositional homogeneity. Many peak overlaps made interpretation of the pattern very difficult. Consideration of the relative intensities of chabazite and thomasite led to the realization that some sharp peak had an intensity contribution from a third phase, which turned out to be wairaikite.
J.S.Huebner, J. Pickrell, T. Schaefer, written communication(USGS 1994)
END_XRD_ANALYSIS.
COMPOSITIONAL_ANALYSIS_TYPE: None # XRF, EM(WDS), ICP(Trace), WChem
COMPOSITION_TRACE: None
COMPOSITION_DISCUSSION:
None
END_COMPOSITION_DISCUSSION.
MICROSCOPIC_EXAMINATION:
96 vol% Chabazite
2 vol% other phases including magnetite
2 vol% Fe-stained grains
avg. grain size = 275µm
Clear grains, fibrous prismatic cones, low birefringence, very small 2V which is characteristic of the Chabazite group. G. Swayze
END_MICROSCOPIC_EXAMINATION.
SPECTROSCOPIC_DISCUSSION:
END_SPECTROSCOPIC_DISCUSSION.
SPECTRAL_PURITY: 1a2_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 884 | 0.2-3.0µm | 200 | g.s.= 275 µm |
| LIB_SPECTRA: | splib05a r 7766 | 0.2-3.0µm | 200 | g.s.= |
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