Ammonio-Smectite

Spectrum Details

Modality

NIR

Category

mineral

Material Type

Phyllosilicate

Sample ID

GDS86

Collection Locality

Synthetic

Spectral Purity

1b2_3_4_ # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns

Composition / XRD

None # XRF, EPMA, ICP(Trace), WChem

Sample Description

IMAGE_OF_SAMPLE:

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 Angstroms, 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.

X Units

cm⁻¹

Y Units

Absorbance

Data Points

2,126