Dinhur Castle, its Gardens and Gardeners. 109 



the quartz of the granite, a tolerably good soil is produced 

 sufficient to bear corn crops when properly cultivated and ma- 

 nured. 



From granite he proceeded to gneiss, and showed them the dif- 

 ference between the two rocks, although composed of nearly the 

 same sort of materials, namely, felsjiar, quartz, mica, and horn- 

 blende; pointed out to them how granite was granular, and 

 gneiss was granular and slaty ; and how that a great part of 

 the Highlands of Scotland is composed of strata of gneiss, and 

 that vegetation, in those districts where gneiss abounds, is ge- 

 nerally thought to be more productive than where granite 

 abounds. He next showed them specimens of mica-slate, telling 

 them that they were composed chiefly of mica and quartz , and 

 that Ben-Lomond, Ben-Ledi, and other parts of the Grampian 

 Mountains, were mostly composed of it. He showed them two 

 varieties of it ; one abounding with garnets, the other without 

 them. Next followed specimens of clay-slate from various 

 slate quarries in Scotland, such as Aberfoil, Callender, and 

 other places where roofing slate is found; in some slates iron 

 pyrites abound, others are without them. On the banks of 

 Loch-Lomond it may be seen dipping into the water, and rising 

 again on each side of the loch ; and may be compared to " a 

 bonnie blue ribbon " thrown across the breast of the Grampians. 



Next followed primary limestone, quartz rock, and serpentine. 

 Primary limestone, he told them, was sometimes called statuary 

 marble, and that some beautiful specimens of it were found in 

 the North of Scotland. It is of a granular and crystalline 

 texture, and some kinds of it take a very fine polish. Much of 

 the marble that was used by the ancients was obtained from 

 Mount Pentelicus in Attica, and also from the Island of Paros, 

 as well as from Moimt Hymettus, Lesbos, and other places ; and 

 much that is used by the moderns is obtained from the quarries 

 of Carrara. Quartz, he told them, was also found in the primary 

 formation, and there were many varieties of it. The Cairngorm 

 stone, or rock crystal, is one variety of it ; and the common, 

 or amorphous, quartz is another. He also showed them some 

 beautiful varieties of serpentine rock from Portsoy ; a rock com- 

 posed chiefly of magnesia, silica, and iron. After making them 

 acquainted with the order of superposition of the rocks of the 

 primary formation, and also pointing out the character of each, 

 he proceeded to inform them that many of the metals were 

 found in veins in the rocks belonging to the formation they had 

 just been considering ; and the richest mines in Cornwall, where 

 cojDper and tin ores were obtained, were in the primary clay- slate 

 resting on granite ; also the mine of Valenciana, at one time the 

 richest in Mexico, where gold and silver were obtained, tra- 

 versed the clay-vslate and porphyry. 



3d Ser. — 1843. III. i 



