The Clinch Sandstone is a mature quartz arenlte or orthoquartzite
of Early Silurian age (also referred to as "Clinch Mountain Sandstone") that is recognized in northeastern Tennessee (Driese, 1988), eastern Kentucky (Englund and others, 1963), and southwestern Virginia (Miller and Fuller, 1947) (Figure 13) (Plate 1).
Prior to this, silcrete artefacts were often identified as silicified sediment, orthoquartzite
or quartzite (see discussions in Hughes et al.
These finds include pre-historic quarry sites containing an orthoquartzite
type new to archaeology, the remains of previously unrecorded pre-Civil War mill sites, and a culvert built of Miocene orthoquartzite
on one of Mississippi's first railroads.
The Chimu, about 80-600 m thick, consists of generally medium-bedded, medium-grained to pebbly, pure quartz sandstone or orthoquartzite with local interbeds of pebble conglomerate.
Faults and fractures normal to the trend of the Algamarca anticline cut orthoquartzite of the Chimu Formation and a K-silicate-altered porphyry stock.
At the Beartooth Island property, sedimentary rocks of the Athabasca Basin are gently dipping, and consist essentially of orthoquartzite
with numerous thin beds of siltstone, mudstone and occasional sub-arkose.
Material from a range of sources was present, including metasomatised argillite, chert, greywacke, obsidian, orthoquartzite
Hughes (1963) studied orthoquartzite
boulders along the Coal Bluff outcrop in southwestern Union County, Mississippi, which he recognized as weathered remnants resting on unconsolidated "Wilcox" sands.