Dr. Mac Culloch on the Geology ofGten Tilt, 283 



as long as these quarries remain accessible to us. For that higher 

 class of sculpture on which the powers of genius are exerted, the 

 proportion between the price of the wrought and unwrought 

 article, (to use commercial phraseology) is so unequal j that no 

 difference in the value of the raw material can compensate for even 

 the most trivial defects in its quality. But there remains even in 

 the class of the fine arts a great number of uses to which the 

 marble of Glen Tilt might with advantage be applied. Such are 

 all those works in architectural decoration, in which absolute 

 whiteness and uniformity of colour, are not only unnecessary, but 

 from their dazzling effect even injurious. The subdued tone and 

 slight air of antiquity given to this marble by its stained and 

 unequal colour would in these works render it of the greatest use. 

 Its durability for the purposes of interior architecture must also be 

 equal to that of Carrara, although there is little doubt that when 

 exposed to the action of the weather it would like the Pentelic be 

 liable to corrosion in those parts vsrhich abound in mica. 



Besides mica, steatite and noble serpentine are found mixed with 

 the white marble. The colours of these substances offer various 

 gradations from bright yellow down to the darkest sap green. 

 It is by these admixtures that the green and white marbles which 

 form by far the largest portion of these beds are produced. The 

 colours are so variously mixed, blended, and dispersed throughout 

 the stone that numerous varieties are the result ; and these are 

 further increased by the occasional presence of dark lead blue. 

 This mixture of serpentine with marble is by no means uncommon 

 in Scotland. On the contrary it may be said that all the white 

 marbles found in this country contain it in a greater or less degree. 

 It is common in the white marble of Sky and in that of Balahulish, 

 In that of Assynt it is more rare, but it occurs also abundantly in a 



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