Shale typically exhibits varying degrees of fissility. Because of the parallel orientation of clay mineral flakes in shale, it … See more

Shales are typically gray in color and are composed of clay minerals and quartz grains. The addition of variable amounts of minor constituents alters the color of the rock. Red, brown and green colors are indicative of … See more

The fine particles that compose shale can remain suspended in water long after the larger particles of sand have been deposited. As a result, shales are typically deposited in very slow moving water and are often fo… See more

Shale is the most common source rock for hydrocarbons (natural gas and petroleum). The lack of coarse sediments in most shale beds reflects the absence of strong currents in the waters of the depositional basin. Thes… See more

Before the mid-19th century, the terms slate, shale and schist were not sharply distinguished. In the context of underground coal mining, shale was frequently referred to as slate well into the 20th centur… See more