50 TIREY. GEOLOGY. 



thin laminae with great facility, marking a structure once 

 probably stratified. It contains occasionally large con- 

 cretions of black and shining hornblende, of two inches or 

 more in length, but is most distinguished by the quan- 

 tity of augite dispersed through it, to which its beauty, as 

 an ornamental marble, is principally owing. The effect 

 arises from the contrast of the dark green spots with the 

 reddish tone of the ground. In consequence of its hard- 

 ness it has fallen into disuse, although, even under that 

 inconvenience, it is still cheaper than many foreign marbles 

 of far inferior beauty*. The quarry has been ill wrought, 

 and indeed nearly ruined by gunpowder, having been 

 managed apparently by workmen ignorant of the use of 

 the feather-wedge or other modes of raising unstratified 

 rocks. About half of it seems to remain untouched; but 

 much even of that is split by the mines used in detaching 

 the blocks which have been quarried. 



Not far from the house of Balphetrish, and in the vici- 

 nity of the rock now described, another considerable mass 

 of limestone occurs. It is equally irregular, but of ten 

 times the size of the former, and like that, bounded on 

 all sides by gneiss. It has been quarried, apparently 

 for the sole purpose of building dykes, at least I could not 

 hear that it had been used for the purposes of ornament. 

 It bears a considerable resemblance to the former in 

 composition, but contains many more varieties of the py- 

 roxene by which that is characterized. The basis of this 

 marble is white. When pure, it is equally snowy in aspect 

 with the marble of lona, which it also resembles in 

 texture and fracture, except that it has no where a 

 schistose tendency. In most parts, however, it is impure, 

 even where it contains no imbedded mineral; breaking 



* Such has generally been the public caprice with regard to our na- 

 tive productions that scarcely an ornament exists in Britain of the beauti- 

 ful serpentine of Portsoy, although in the reigns of James the Fifth and 

 Mary it was wrought and exported to Paris, where specimens of it 

 may now be seen among the interior architecture of many houses. 



