494 PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 





It is that of a mineral which is found imbedded in the granular massive 
dark-green serpentine of the Balhammie Hill, near Colmonell, in Ayrshire. 
Dr James GEIKIE, who surveyed this district, calls it Bronzite. A very 
similar, if not identical substance, is found at Knockdow Hill, Lendalfoot, and 
Byne Hill, Girvan. 
The mineral has much resemblance to the enstatitic, or pale variety of 
bronzite ; it is of a pale, somewhat greyish olive-green colour, a greasy sub- 
vitreous lustre, and is very soft. 
Through the kindness of Professor GEIKIE, a sufficiency of fragments from 
specimens collected by the officers of the Survey was put into my hands. The 
imbedded crystals were about one-fourth of an inch in size; their form could 
not be made out. They had somewhat of a fibrous structure, were semi-trans- 
parent, and had an appearance between that of schiller-spar and diallage. 
1°313 grammes yielded— 
Silica, 2 : °491 
From Alumina, . °005 
*496 = She iG 
Alumina, . , : 5 oa hee 
Ferric Oxide, 069 
Ferrous Oxide, . ; Be 095 
Manganous Oxide, . : 076 
Magnesia, : : . 37°014 
Potash and Soda, . . traces. 
Water, . ; : . 16°07 
100 : 223 
Loses in bath, 3 - 957 per cent. of water, beyond the above. Was probably 
impure from non-separable serpentine, to the extent of about 1 per cent. 
The total absence of lime seems to indicate that this is an altered enstatite. 
Be this as it may, the change is the same as that of augite. Enstatite, however, 
changes less rapidly, and seems to retain, after alteration, much of its original 
lustre. 

Change by Hydration; removal of Lime; of Silica; and total peroxidation, 
but no removal of the Iron. 
23. The smaller—the more easterly of the two beds of serpentine to the 
west of Portsoy—has an internal structure and appearance which is quite 
unique. 
