HELIOTROPE. 221 dinia, and Bohemia. In Scotland, a variety of mineral nearly resembling heliotrope, occurs in the island of Bum. Uses. This mineral was well known to the ancients, who have left us accurate descriptions of it. Figures were seldom cut upon Heliotrope until after the commence ment of the Christian era, when representations of reli gious subjects, were often engraved upon it. There is a fine engraved stone of this kind in the National Library in 1'aris, representing the head of Christ jiagellj, so cut that the red spots are made to represent drops of blood. It ls also cut into seals, snuff-boxes, and other ornamental nrticles. The varieties having the greatest degree of transparency, and most numerous red spots, are the most highly prized : these are found in Bucharia. The Sibe- r, an varieties are destitute of red spots. Observations. 1. It is distinguished from Common Calcedony by its Colour, fracture, lustre, and transparency. 2. It is Calcedony, intimately combined with Green Earth . 3. Its fracture and transparency shew that it is a spe- c *es intermediate between Calcedony and Jasper. E The name Heliotrope is of Greek extraction, from iA ‘ a? > sun, and to turn. According to Pliny, it re eved this name because it was used for solar observa tions. 8. Siliceous