Rock Salt
common salt, or chloride of sodium, occurring as a mineral and in a solid form. It is always mixed with various impurities. It is found massive or crystallized, its crystals generally cubes, its masses very often either granular or fibrous. It is white, gray, or, owing to the presence of impurities, more rarely red, violet, blue, or striped. For its chemical and other qualities, see SALT.
It is a very extensively-diffused mineral, and in some places forms great rock and even mountain masses. A hill of rocksalt near Montserrat, in Spain, is 500 feet high. The island of Ormus, in the Persian Gulf, is formed of rock salt. The Indus, in the upper part of its course, forces its way through hills of rock salt.
ROCK SCORPION (Buthus or Scorpio afer), a species of scorpion found in Africa, averaging about six inches in length. The bite of this animal, though not absolutely fatal, is yet considered to be dangerous.