ROCK CRYSTAL. 177 rocks and mountains. 1 It may be described as a dense, opaque, siliceous rock, of red, purple, blue, and greenish tints, with their modifications; and according to the arrangement of these we have the following varieties:— i. Riband jasper; in which the colours are arranged in parallel bands. 2. Egyptian jasper; found imbedded in trap, or as pebbles on the banks of the Nile, in which shades of wood-brown, alter nating with red, are arranged in concentric wavy zones, which are usually cut across and polished. 3. Ruin jasper; a variety presenting a fanciful resemblance to ruins. There are also, 4. Yellow jasper ; found at Yourla in the bay of Smyrna; and, 5. pebbles of Red jasper ; on the plains of Argos. 2 (f) Blood stone, or heliotrope, has a deep green base, slightly translucent, containing spots of red, which have some resemblance to drops of blood. In the Louvre at Paris, there is a bust executed in this stone, in which the spots are so arranged as to represent drops of blood. 3 Jasper is not uncommon amongst the more ancient geological formations. It is abundant in large pebbles or boulders amongst the conglomerates of Mweelrea mountain in the West of Ireland; along the shores of Co. Wexford; and in smaller ones, 1 A fact well expressed by Mr. Ruskin in ‘ The Two Paths,’ Lect. 5. 2 Bristow, Glos. Min. p. 195. 3 Dana, Man. Min. p. 137. N
