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(For further information on spectrsocopy, see:
http://speclab.cr.usgs.gov)
TITLE: Ammonio-Smectite GDS86 (Sy) DESCRIPT
DOCUMENTATION_FORMAT: MINERAL
SAMPLE_ID: GDS86
MINERAL_TYPE: Phyllosilicate
MINERAL: Ammonium_Smectite (Synthetic)
FORMULA: (NH4)0.33(Al,Mg)2Si4O10(OH)2*nH2O
FORMULA_HTML: (NH4)0.33(Al,Mg)2Si4O10(OH)2•nH2O
COLLECTION_LOCALITY: Synthetic
ORIGINAL_DONOR: Dennis Krohn, USGS Reston
CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory
ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory
SAMPLE_DESCRIPTION:
END_SAMPLE_DESCRIPTION.
XRD_ANALYSIS:
40 kV - 30 mA, 6.5-9.5 keV
File: amsmec86_mdi (smear on quartz plate)
References: PDF2 #13-0259 43-0688 33-1161; Brindley and Brown (1980)
Found: Possible dioctahedral ammonium smectite, quartz
Comment: All reflections are broad; the alpha1-alpha2 reflections of quartz
are not resolved, even at high values of 2 theta. Clay reflections show only
minor asymmetry toward smaller d-spacings. Search-match based upon strongest
lines returned quartz and sepiolite, profile-based search-match returned quartz
and rectorite. Neither pair satisfactorily explained the observed pattern. Manual
search was initiated to identify the non-quartz peaks at 12.2, 4.46, ~3.23,
~2.57, and 1.499 angstroms by visual comparison with patterns of clay-type minerals.
No single phase gave a good match. The most adequate fits were given by 14 angstroms
montmorillonite (13-0259), which does not have a prominent reflection near 1.50
angstroms, and another dioctahedral smectite, volkonskoite, which does not account
for the observed 3.27 angstrom reflection. The observed basal spacing, 12.2
angstoms, is smaller than the basal reflections of any other smectites in the
PDF2 database. A summary table in Brindley and Brown (1980, p.203-204) shows
that substitution of NH4 for any other interlayer cation reduces the basal spacing's
of a variety of smectites to 11.7-12.5 angstroms at 32-79 percent relative humidity,
and slightly greater in water.
END_XRD_ANALYSIS.
COMPOSITIONAL_ANALYSIS_TYPE: None # XRF, EM(WDS), ICP(Trace), WChem
COMPOSITION_TRACE: None
COMPOSITION_DISCUSSION:
END_COMPOSITION_DISCUSSION.
MICROSCOPIC_EXAMINATION:
END_MICROSCOPIC_EXAMINATION.
SPECTROSCOPIC_DISCUSSION:
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: | splib04a r 311 | 0.2-3.0µm | 200 | g.s.= |
| LIB_SPECTRA: | splib05a r 902 | 0.2-3.0µm | 200 | g.s.= |
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