Argillite

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"Argillite" may also refer to Argillite, Kentucky.

Image:Chacoan turquoise with argillite.jpg

A selection of Ancestral Puebloan (Anasazi) turquoise and orange argillite inlay pieces from Chaco Canyon (dated ca. 1020–1140 CE).

An argillite (pronounced /ˈɑrdʒɨlaɪt/) is a fine-grained sedimentary rock composed predominantly of indurated clay particles. Argillites are basically lithified muds and oozes. They contain variable amounts of silt-sized particles. The argillites grade into shale when the fissile layering typical of shale is developed. Another name for poorly lithified argillites is mudstone. These rocks, although variable in composition, are typically high in aluminium and silica with variable alkali and alkaline earth cations. The term pelitic or pelite is often applied to these sediments and rocks. Metamorphism of argillites produces slate, phyllite, and pelitic schist.

The Haida carvings of Queen Charlotte Islands along the coast of British Columbia are notable aboriginal art treasures created from variably colored argillites.