HistoryClays are secondary minerals that have formed through the weathering and hydrous alteration of certain parent rocks and their constituent minerals. Common igneous and metamorphic rocks such as granites, gneisses and schists contain minerals such as feldspars, hornblendes, micas and other complex alumina silicates. Silica and alumina are necessary precursors to the formation of clay minerals. Long periods of physical weathering breaks down the rocks into finer, grain sizes and allows an accelerated rate of chemical weathering ore mineral decomposition to take place. In some cases, the decomposition takes place in situ and the alteration products may accumulate at the site of origin or be carried away by water and winds. Often fine grained weathering products (mixed sands, etc.) will be transported from the site of origin, redeposited as clastic beds and later subjected to chemical weathering and alteration. Clays formed at the site of the parent rock are called primary clays even though they are secondary in origin after other minerals. These formed after transportation and redeposition of rock and mineral fragments or transported as clays from the original site of origin are called secondary clays. Saskatchewan industrial clays are secondary in that they or their immediate precursors have been transported and redeposited. The important clays of the Whitemud Formation are an example. Usually secondary clays are mixed with other minerals such as micas and quartz which are more resistant to weathering. Sometimes, as in the case of the upper beds of the Whitemud Formation, reworking by stream and wave action will separate the clay from the unweathered grains, break the latter down to finer grain sizes and carry the clay away to be redeposited after as distinct beds. Such a process is believed to have given rise to the important deposits of plastic ceramic clays in southern Saskatchewan. Clays that remain mixed with quartz sand grains and other minerals may also be of economic significance. The lower beds of the Whitemud Formation, known as kaolized sands, are an example. These beds contain an average of 50 per cent kaolin which can be separated, purified and used in a variety of industrial applications. Occasionally the parent material may be completely weathered to clay minerals. Such is the case with the bentonites near Truax., which were formed as a weathering product of volcanic ash deposited during the late Cretaceous period.
Description of MineralClay is a general term for a highly variable group of natural materials that are soft, earthy, extremely fine grained, usually plastic when moist and consisting of one or a mixture of various clay minerals and impurities. Alkalies such as sodium, lithium and potassium and alkaline earths such as magnesium, calcium and barium are often present in the molecular structure of clays and have a significant effect in the physical and chemical properties. Clays occurring in nature rarely comprise pure, single clay minerals. They usually contain a variety of non-clay impurities such as quartz, calcite, mica, feldspar and pyrite, among others. Most clay minerals involve two basic types of units in their atomic structure. The manner in which theses units are combined and the type of exchangeable atoms that are present will play a very significant role in the type of clay mineral that forms. The major clay resources are:
In Saskatchewan, the most important commercial clays include the kaolinite, montmorillorite and illite clays. Saskatchewan clays based on the
LocationKaolin and related clay resources of economic importance are located in southern Saskatchewan. Important deposits of kaolin or associated plastic ceramic clays are found in the areas of Eastend, Wood Mountain, Readlyn, Willow Bunch, Rockglen and near Claybank in the Cactus and Dirt Hills. The most significant resources occur in the Cretaceous Whitemud and Tertiary Ravenscrag Formations. Glacial lake clays are scattered widely throughout the province. Some of the most extensive deposits are situated in the Regina and Saskatoon areas and in western areas between Unity and the Great Sand Hills.
Mining - Producers of ClaysClay and clay products are produced by three major companies in Saskatchewan.
Current production is restricted to face brick for Canadian and American markets and stoneware clay for the Canadian market.
Uses for ClayClays play a very important role in many industries. Their use depends upon their physical and chemical properties. Clays can be divided into three categories (depending on their uses):
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