500 SYSTEMATIC DESCKIPTION OF PRECIOUS STONES 



deposits, especially of iron. Sometimes it is found in the joints and crevices of siliceous 

 rocks, and at other times at spots where certain igneous rocks of the greenstone (diabase) 

 family have intruded into clay-slates, jasper being an alteration or contact product of the 

 latter. Irregular masses of jasper are referred to, independently of their colour, which is 

 usually yellow, brown, or red, as common or German jasper, in contradistinction to the red 

 or chestnut-brown ball-jasper, which occurs as regular nodules or balls in brown iron-ore, 

 or loose on the surface of the ground. All kinds of jasper are of course very common as 

 pebbles in the sands and gravels of rivers and streams and other alluvial deposits. 



The different varieties of jasper have been much used as ornamental stones, especially 

 in ancient times, when the stone was engraved, set in mosaics, and fashioned into objects of 

 some size. Its application in the Middle Ages, and in comparatively recent times, was also 

 extensive, but it has now fallen almost into disuse. Specially fine stones of uniform colour 

 are sometimes cut up for gems, and in spite of the dulness of the fractured surface they 

 take a fair polish, although the lustre is never very strong. The stone is principally used, 

 however, for boxes, bowls, vases, table-tops, and small ornamental edifices. The construction 

 of such objects may be accomplished with one large block, or it may be necessary to use 

 several pieces, in which case they must be chosen with due regard to colour. Jasper is too 

 abundant to be worth very much, and the value of all but exceptionally fine and uniformly 

 coloured specimens is small. 



Some of the colour-varieties of jasper occur singly and only at certain places, while at 

 other places jaspers of several different colours are found. Owing to the wide distribution 

 of this stone only the most important localities will be here enumerated. 



Typical red jasper is represented bv the ball-jasper of Auggen and Lie], near 

 Miihlheim, in Breisgau. It occurs there as rounded nodules, ranging in size from that of a 

 nut to that of a man's head, in brown iron-ore, with which it is mixed. The nodules are 

 coated with white marl ; in the interior they are of a dark, tile-red colour with white, 

 yellow, or greenish stripes or markings. 



Fine red jasper (or ferruginous quartz) sometimes traversed by veins of white quartz, 

 occurs not infrequently to the west of Marburg, in Hesse, also in Nassau and other places 

 in Germany, being there a contact product of clay-slate near the junction of this with 

 diabase. The dark blood-red colour is very effective when the stone is cut. This red 

 jasper occurs usually in rather small pieces, but blocks the size of a man's head, or larger, 

 are sometimes found. Lohlbach, near Frankenberg, was formerly noted for beautiful 

 jasper occurring in blocks of considerable size, which was known as " Lohlbach agate." It 

 A\as once used to a considerable extent, and many artistic objects, worked in this material, 

 are still preserved in the collection at Cassel. 



Fine red jasper, as well as that of other colours, is found in the veins of iron-ore in 

 many places in the Saxon Erzgebirge. Fine specimens of all colours are of frequent 

 occurrence in the British Isles, particularly in Scotland. 



Brown jasper is represented by the Egyptian jasper, sometimes called Nile jasper, 

 although it does not come from the Nile. It is found in rather rough rounded nodules, on 

 the smooth fracture of which there are concentric brownish-yellow bands alternating with 

 the dark chestnut-brown colour of the rest of the stone. These nodules have been derived 

 from the beds of the Nummulitic formation ; they occur in large numbers on the sserir or 

 stony areas of the Egyptian desert. There is a sserir to the east of Cairo, on the slopes of 

 Jebel Mokattam, and over large areas of the Lybian desert there is nothing to be seen but 

 rounded fragments of jasper. The rounding of these fragments has been effected not by 

 water but by the action of wind-blown grains of sand. 



