THE MINERALOGY OF SCOTLAND. 



351 



that their section, according with that of the lamella of the schist, exhibits an appear- 

 ance of curved pencilliform groups of acicular crystals, frequently an inch in length, 

 assuming an appearance of great singularity. In this direction the schist is visible, and 

 appears to form the largest part of the stone, while in the cross fracture, the lamellae of 

 hornblende alone being seen, the whole rock seems to consist of this mineral. Occasion- 

 ally the hornblende displays crystals disposed in so many different ways that the schist 

 is discernible even in the cross fracture." 



To this description I have only to add that the specimens I have obtained from near 

 Auchlankart were all of the rhsetizile or grey variety, much impregnated with the sub- 

 stance of the schist, in which indeed I alone here found them, but that I found at the same 

 spot — which is at the upper fork of the burn — crystallised staurolite in simple crystals, 

 the mode of the occurrence of which — as regards the quartz and the rock matrix which 

 alike hold them — was precisely as described by Macculloch for disthene. These crystals 

 of staurolite were amber coloured and transparent, but had a central structure, which 

 will be noticed below. 



Specimens nearly as fine as those from Botriphnie were formerly found by Colonel 

 Imrie loose lying in the neighbourhood of Millden and the Burn of Turret, North Glen 

 Esk, Forfarshire. One of these has been figured by Sowerby, vol. iii. p. 49. Here also 

 nargarodite is the sole associate.* 



" Near Banchory, in Aberdeenshire," " near Mortlach, Banffshire," and " in quartz 

 lear the summit of Ben y Gloe," in blue radiating crystals, in quartz nodules, in clay- 

 late, in limestone at Ardonald, by Cunningham, are old localities at which this mineral is 

 10 longer found. 



It has long been known, and is still found at Vanleep, Hillswick, Shetland. At this 

 ;ash, a chasm in the cliffs of the western shore of Hillswick, kyanite occurs of three 

 narkedly dissimilar appearances. 



The ordinary blue crystals generally isolated and imbedded in massive quartz are 

 ere very rare. Large plumose groupings of a reddish -grey colour, also occurring 

 solated in massive quartz, are less rare ; but the common appearance is that of veins or 

 irge isolated nodules of smaller intermatted crystals of an anchovy-red passing into 



* I analysed a specimen from Colonel Imrie's collection, and obtained on 1*3 grammes : — 



Silica, ...... 36-384 



Alumina, . 



Ferric Oxide, 



Ferrous Oxide, 



Lime, 



Potash, 



Soda, 



Water, 



The loss in bath was 

 The insoluble silica, 

 The specific gravity, 



58-296 

 1-609 

 1123 



•861 



■252 



•423 

 1-445 



100-393 



'282 per cent. 

 1-691 „ 

 3538 „ 



