"Refractory" items according to any standard English dictionary are materials which are hard to work with, and are especially resistant to heat and pressure. In practical terms, refractories are products used for high temperature insulation and erosion/corrosion and are made mainly from non-metallic minerals. They are so processed that they become resistant to the corrosive and erosive action of hot gases, liquids and solids at high temperatures, in various types of kilns and furnaces.
Basalt is a naturally occurring siliceous refractory product. It was formed many, many years ago - and is still being formed in lava flows from volcanic eruptions - under the natural geological forces of heat and pressure. Modern refractory production is largely a replication of this process of forming naturally-occurring (or synthetic) non-metallic mineral oxides (and some non-oxides like carbides or nitrides) under the bonding conditions of high heat and pressure. Of course with technological progress, alternative bonding techniques, such as with chemicals, cements, resins, etc. have also developed.
Because refractory products are so resistant to heat, erosion and corrosion, they are typically used in any process involving heat and corrosion such as in kilns and furnaces. According to the main chemical component, i.e. fire clay, or magnesia, or zirconia, etc. they are commonly known as alumino-silicate or acid refractories, basic refractories, and neutral refractory products.
In physical characteristics, refractories typically have relatively high bulk density, high softening point (or Pyrometric Cone Equivalent), high crushing strength. They are produced as standard bricks, or as shapes (including hollow-wares) or as granular or unshaped or monolithic products.
The principal applications of refractories are in iron and steel industries, cement, glass, non-ferrous metals, petro-chemicals and fertiliser industry, chemicals, ceramics and even thermal power stations and incinerators.
The development and application of refractories for various industries, testing procedures of properties and so on are covered in the English language, by a number of well-known technical journals, such as The Bulletin of the American Ceramic Society, Taikubutsu Overseas, Interceram, Ceramic News, Refractories Applications, IRMA Journal, Transaction of the Indian Ceramic Society, Metal News, etc