In ancient times the minerals comprising or included in this important group were commonly known by the name Lapis Nephriticus or Kidney Stone, and from this name in the 18th century Dr. A. G. Werner suggested the term Nephrite. To the Nephrite varieties the general term Jade is universally applied. The name occurs in old writings as jad and jadde, and is derived from the Spanish Hijada, kidney. Sir Walter Raleigh in 1595 wrote of this “kinde of stones which the Spaniards call Piedras Hijadas and we use for spleene stones.” Chemically the species included under the name “jade” are not the same, the nephrite jade being a silicate of lime and magnesia and the jadeite a silicate of sodium and alumina, but the modern scientist in common with the ancient scientist binds them together under the one denomination—kidney stone. In the 19th century Professor A. Damour demonstrated the chemical difference between jade and jadeite. The well-known Camphor Jade of China is a white jadeite, some specimens containing certain percentages of Chromium exhibiting those apple-green patches so highly praised by gem collectors. Burmese Jade, known as Chauk-Sen, (which since the 13th century has been principally exported to China) is chiefly jadeite, and the Imperial Jade of charming pale or apple-green colour, known as Feitsui and set down by some writers as chrysoprase, is more properly Prehnite. The nephrite charms—Piedras Hijadas—known in Mexico as Chalchihuith when the Spanish invaded that country were probably jadeites. The Chinese have held the jade family in the highest esteem and reverence for many centuries, and it poetically expresses to them all the virtues of many precious stones blended together. It is said that most of the nephrite used by them came from the Kuen-lun mountains in Turkestan, but the discovery of the mineral at no great distance from Peking in 1891 helped to make that city a great working centre. The Chinese word for jade is YU, expressed in their hieroglyph as a cross over a kind of semi-circle. Jade stone they know as YU-CHI, and precious objects of jade as OUAN YU. The words KHITCHINJOU-YU indicates a gem rare as jade, and the Imperial Academy was known as Jade Hall. The Turkestan name for jade closely resembles the Chinese YU in its form YASHM, YUSHM or YESHM.