Minerals and Crystals
MINERALS AND CRYSTALS. The word mineral is derived from the Latin minare, to mine, and was originally used to include all rocks which were obtained through mining. Nowadays, the word mineral is used to describe those materials of the earth’s crust formed by the inorganic processes of nature, which have a definite chemical composition and whose constituent atoms are arranged in a consistent pattern. Rocks, on the other hand, are defined as aggregates of one or more minerals. Most rock types are composed of several different minerals; of those made up of only one mineral, the best known is marble, which is formed of interlocking crystals of calcite.
The name crystal, which was first used to describe rock-crystal, the clear, transparent form of quartz, has its root in the Greek word krystallos, meaning ice. In the early Middle Ages and before, it was thought that rock-crystal was made of ice which had been so intensely frozen that it could never again melt.