Ceramics

Ceramics have been used by man since antiquity. The earliest ceramic articles were made from naturally occurring materials such as clay minerals. It was discovered in prehistoric times that clay materials become malleable when water is added to them, and that a molded object can then be dried in the sun and hardened in a high temperature fire. The word ceramic comes from

the Greek word for burnt material, keramos. Many of the same raw materials that were used by the ancients are still used today in the production of traditional ceramics. Traditional ceramic applications include whitewares, heavy clay products, refractories, construction materials, abrasive products, and glass.

Clay minerals are hydrated compounds of aluminum oxide and silica. These materials have layered structures. Examples include kaolinite, halloysite, pyrophillite, and montmorillonite. They are all formed by the weathering of igneous rocks under the influence of water, dissolved CO₂, and organic acids. The largest sources of these clays were formed when feldspar was eroded from granite and deposited in lake beds, where it became altered to a clay.

Silica is a major ingredient in glass, glazes, enamels, refractories, abrasives, and whiteware. Its major sources include quartz, which is made up primarily of sand, sandstone, and quartzite.

Feldspar is also used in the manufacture of glass, pottery, enamel, and other ceramic products. Other naturally occurring minerals used directly in ceramic production include talc, asbestos, wollastonite, and sillimanite.