New Galilee, Pennsylvania
Clay was an abundant resource in Beaver county. According to the 1955 circular of the Pennsylvania Geological Survey, In 1955 Beaver County produced 13.7% of Pennsylvania's total clay output. There were 13 companies that mined clay in Beaver county at that time. Two of these companies, The Negley Fire Clay Co. and Ralph A. Veon, Inc. mined fire clay of the plastic variety from open pits and marketed the output for use in manufacturing fire brick and block, foundries, and heavy clay products. In addition, Ralph A. Veon, Inc., mined and sold fire clay of the burley variety. In 1955, New Castle Refractories mined stoneware clay from an underground mine near New Galilee for use locally in manufacturing pouring channels
Ancient Egyptian pottery
The marl clay (or 'desert clay') is found along the Nile valley, from Esna to Cairo, in the Oases and at the edges of the Nile Delta. It is a yellow-white stone, which is found in limestone deposits. The deposits were created in the Pleistocene, when the original Nile river and its tributaries deposited this clay in what had previously been desert. Marl clay includes a range of kinds of clay based on their base substance. In general, they have a lower percentage of silicum and significantly higher calcium content. The most important sub-types of marl clay are:Marl clay is normally cream or white in colour when it is fired in an oxygen-rich oven. Cuts can reveal pink or orange areas. It is rich in mineral salts, so the outer surface often has a thin layer of weathered salt which forms a white surface layer when fired, which can be mistake for a 'glaze' by the unwary. At higher firing temperature (c. 1000 °C), this layer becomes olive-green and resembles a green glaze.