Clay-sized quartz produced by crushing
Although sand and silt-sized quartz have been studied extensively, clay-sized quartz has received scant attention, despite the fact that its nature and production are of considerable interest to sedimentologists, geochemists, and workers in the field of environmental health. Blatt and Schultz have shown that the quartz content of mudstones is about 28%, and of that portion, about 15% is clay-sized (1). The bulk of fine grained quartz in recent sediments and man's immediate environment is produced by crushing or breaking of larger particles during transport and abrasion. Comminution of quartz produces surface structural changes, disrupted lattice zones or conversion to glass (2). Experimental models of earthquake fault zones using quartz sandstone as sliding surfaces have produced quartz and glass <0.06μm in diameter (3). Larger claysized quartz particles (>1μm) have been characterized (4); however, an attempt to differentiate quartz and glass <0.5μm has met with only limited success (3). High resolution transmission electron microscopy (HRTEM) now permits new opportunities to examine very fine grained material, as indicated below.