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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: 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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