By Harold McGee
Ceramics are varying mixtures of a number of different compounds, notably the oxides of silicon, aluminum, and magnesium. Glass is a particular variety of ceramic whose composition is more regular, and usually includes a preponderance of silica (silicon dioxide). Until fairly recently, these materials were made from naturally occurring mineral aggregates: the word ceramic comes from the Greek for “potter’s clay.” The molding and drying of simple clay pottery, or earthenware, dates from about 9,000 years ago, or about the time that plants and animals were first domesticated. Less porous and coarse than earthenware, and much stronger, is stoneware, which contains enough silica and is fired at a high enough temperature that it vitrifies, or becomes partly glass. The Chinese invented this refinement sometime before 1500 BCE. Porcelain is a white but translucent stoneware made by mixing kaolin, a very light clay, with a silicate mineral, and firing at high kiln temperatures; it dates from the T’ang Dynasty (618–907 CE). This fine ceramic was introduced to Europe with the tea trade in the 17th century, and in England was first called “Chinaware,” and then simply “China.” The first glass containers were not molded or blown, but laboriously sculpted from blocks, and date from 4,000 years ago in the Near East.