PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 495 
It protrudes out of the grass-clad bank and extends northward for some 
hundred feet, terminating in the sea. As it dips at a high, almost a vertical 
angle, it much resembles an intrusive dyke, for which it has indeed been 
taken. 
The portion which stands in the water has by wave action been separated 
from the main body, and consists of an altogether unaltered gabbro, with bright 
green diallage crystals of the size of peas, imbedded in a paste of ladradorite. 
The terminal end of the chief mass—that which immediately faces the sea- 
stack of gabbro—is in a much altered, transition state. The augite is grey-green 
in colour, dull in lustre, and much softened ; the felspar has darkened in colour, 
being greyish brown; it is somewhat translucent and of a waxy appearance. 
Unaltered asbestus is associated with it. 
A little further southward the change is completed. What had been the 
felspar is now of a pale-green colour, soft and greasy ;—in fact, it is true ser-: 
pentine. That which now represents the augite has a peculiar appearance. 
The colour is blue-black, the lustre is feeble and glimmering, being reflected 
from apparently a former cleavage plain, there being now little or no fixedness 
in the direction of its fracture. Its specific gravity is 2° 618. 
The appearance is so similar to the hydrophite of Taberg, that it was believed 
before analysis to be that mineral. 
|) The peculiar appearance of the fractured rock results from the isolated and 
| f : t 
_ promiscuous way in which these almost black crystals are sprinkled throughout 
| a paste of yellow-green serpentine, giving an appearance somewhat similar to 
_ that of a leopard’s skin. 
| 1°35 grammes gave— 
Silica, 2 : *445 
From Alumina, . °004 
“449 = 34. : 538 
Alumina, . ; : 2 ASL 2809 
Ferric Oxide, . : » hb +20 
Ferrous Oxide, ; ; -333 
Manganous Oxide, . : * 284 
Magnesia, : : . 36° 384 
Water, . 3 : cele 1:97. 
100 -096 
Here the relative proportions of silica, magnesia, and water are those normal 
to serpentine ; the lime has been totally removed ; none of the iron has appa- 
rently been abstracted, but it has been entirely converted into the higher 
oxide. 
It is a point deserving of much consideration that the portion of this stratum, 
