A POSSIBLE ASSOCIATION BETWEEN A ZEOLITE AND FOSSIL BACTERIA IN AN ANCIENT ALKALINE SALINE LAKE DEPOSIT
To test this hypothesis, the fibrous IR was characterized using optical petrography, scanning electron microscopy, energy dispersive X-ray analysis (EDX), and X-ray diffraction crystallography (XRD). Petrographic analysis reveals abundant crystals, colorless in plane light, of sub-micrometer diameter and mm-scale lengths with a fibrous habit. These crystals exhibit parallel extinction and are length slow. EDX reveals a composition of Si, Al, O, Mg, Na and Ca. XRD indicates that these fibers are zeolite crystals, hydrous alumino-silicates of Na, Ca, and K.
Although exact species identification in zeolites is difficult owing to the similarity of their physical properties, the data suggest that these fibers are erionite, a mineral with a single sixfold ring of silica tetrahedra lying perpendicular to a triad axis. This arrangement produces an open cage-like structure, which, along with the presence of loosely bound water molecules, results in enhanced ion exchange and molecular retention. This increased chemical activity may facilitate the growth of microorganisms.