82 Dr. Mac Culloch's Sketch of the 



I shall now proceed to describe the mineral substances which I 

 observed in Sky, having reserved these details for separate consi- 

 deration, lest they should interrupt the connection of the geological 

 remarks which form the preceding part of this paper. The most 

 numerous, and not the least interesting of these minerals, are those 

 of the zeolite family. They are to be seen in various parts of the 

 island, but are to be found in the greatest beauty and variety in the 

 cliffs of the western shore between Loch Bracadale and Loch Brittle. 

 Talisker, as it is the most accessible of these places, so it presents 

 the richest assortment to the collector of specimens. But in general 

 the mineralogist can have no access to any specimens but those 

 which fall from the cliffs, and have long been exposed to the vio- 

 lence of the sea and the injuries of the air. However splendid 

 therefore, they may once have been, they are not always to be 

 found in a state of good preservation. It is moreover often difficult 

 to gain access to them on any terms, particularly along the other 

 points of this wild shore, since it is so beset with rocks on which a 

 dangerous surf is almost always breaking, that it requires neither com- 

 mon good weather, nor common dexterity in the management of a 

 boat, to effect a landing and retreat without hazard. 



Analcime is the most common of all these minerals on the shore 

 to which I have now alluded, and it is found in the greatest pro- 

 fusion at Talisker. It sometimes occupies cavities of considerable 

 size, in different varieties of the trap, but seems to be by far the 

 most abundant in those earthy and little compact sorts, for which 

 there is no name in our catalogue of terms. In other cases it forms 

 flat druses of considerable extent, occupying the walls of fissures, 

 while in a third, a single crystal is sometimes seen in a cavity just 

 sufficient to contain it. In the greater number of instances the re- 

 maining part of such cavities is filled with the filamentous meso- 



