How Is Clay Formed?
The gradual chemical weathering of rocks, usually silicate-bearing, by low concentrations of carbonic acid and other diluted solvents results in the formation of clay minerals. In addition to the weathering process, some clay minerals are formed through hydrothermal activity.
Clay is formed from earth and various minerals as a result of weather conditions such as heat and rain. Occasionally clay is produced by processes dependent on hot underground springs. Wet clay has much the same consistency as a soft plastic and is capable of containing water. When dry, clay becomes hard and thus takes on a permanent shape. No other material on earth can be used in so many different ways.
There are two types of clay deposits: primary and secondary. Primary clays form as residual deposits in soil and remain at the site of formation. Secondary clays are clays that have been transported from their original location by water erosion and deposited in a new sedimentary deposit. Clay deposits are typically associated with very low energy depositional environments such as large lakes and marine basins.
Clay provides the mechanical and chemical environment for almost all plant life and, therefore, can be said to support all the life on earth. Once extracted from the soil, clays are used in a wide variety of industries, including engineering, paper making, brick making, cement and chemicals. The use of clay in pottery predates recorded history, and it has largely been due to pottery finds that archaeologists have been able to analyze and record past civilizations.