PALYGORSKITE FROM A LOCALITY IN THE SOUTHEASTERN YUCATAN: A POTENTIAL SMALL SCALE INDUSTRIAL GRADE DEPOSIT FOR ENVIRONMENTAL APPLICATIONS

A palygorskite unit was discovered in a road cut of undifferentiated Tertiary limestone between the villages of El Pariso and San Roman (18°49.309 N, 88° 37.861W) in the southeastern Yucatan Peninsula, Mexico.

The palygorskite unit is approximately 1.5 m thick and consists of thin 0.5-1.0 mm lamina. The grain size is approximately 99% clay-sized particles with impurities being calcite and titanium oxides. X-ray diffraction (XRD) indicates that minor amounts of montmorillonite are present and transmission electron microscopy (TEM) investigation indicates that approximately 5-15% of the material is montmorillonite. Soft sediment deformation is common in some portions of the unit and include diaper-like yellow-tan calcite units which comprise 1-2% of the unit.

TEM investigation of the clay indicates that particles are commonly 0.5 to 2.5 micrometers long and 20 to 50 nm wide. Selected area electron diffraction (SAED) data show streaking along (hk0) indicating disorder typical of palygorskite. Energy dispersive spectroscopy (EDS) analyses on individual fibers (n = 50) show that average compositions for major components are 66.56 wt% SiO2, 15.16 wt% Al2O3, 0.40 wt% Fe2O3, 15.42 wt% MgO, 0.48 wt% CaO, 1.58 wt% Na2O, and 0.40 wt% K2O. Chemical compositions are broadly similar to palygorskite fibers found in the Hawthorne Formation of southern Georgia, U.S.A. and other palygorskite localities in the Northern region of the Yucatan Peninsula.

The particle size and the chemical compositions of palygorskite are consistent with palygorskite that has been used in industrial applications. Potential applications include landfill liners, reactive media for tertiary treatment of constructed wetlands, liners for constructed wetlands and drilling mud.

This is the southern most locality of a clay-rich sedimentary unit reported in the literature for the Tertiary carbonates of the Yucatan Peninsula and this occurrence implies a wider range of palygorskite deposition than previously recognized. Palygorskite may be a regional economic and environmental resource that is not fully recognized.