Sioux Quartzite

Specimen: 2014-004

This is a quartzite specimen composed of an interlocking mosaic of quartz grains. The original detrital grains appear to have been rounded and well sorted prior to induration and subsequent metamorphism. Maximum grain size is .9 mm, minimum is .05 mm. The modal size range is from .2 to .5 mm. Grains are well sutured with consertal boundaries, and show no preferential elongation direction. Overgrowth rims are easily identifiable on many grains. Quartz grains overwhelmingly predominate. Grains originating from other siliceous sedimentary rocks, such as chert, contribute less than 1 percent. Opaque grains also occur at random throughout the slide at a frequency under 1 percent. Only a few other accessory minerals (pyroxenes) were noted on the slide. There are no appreciable signs of weathering or alteration visible in the specimen.
7/9/2015 MP