Quartz is made of the chemical elements silicon ... quartzite and marble. Igneous and metamorphic rocks on Earth's surface inevitably erode and break up as wind and water go to work on them.

An Upper Palaeolithic site like this is practically nonexistent. An impressive 277 flint tools, metamorphic rocks, quartz, and hundreds of bones were recovered. Furthermore, researchers found the ...

Geologists recently dated the age of Watersmeet gneiss, a type of rock in the Upper Peninsula, as the oldest in the U.S. Here ...

Michigan, Minnesota and Wisconsin all feature ancient rocks known as gneisses — metamorphic rocks banded with various minerals — but an analysis determined that the gneiss in northern Michigan ...

and they are usually derived from igneous and metamorphic rocks in soil (Lapidus 1987). In most soils, feldspars, micas, and quartz are the main primary mineral constituents, and pyroxenes and ...