
502 PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 
HORNBLENDE OR AMPHIBOLE. 
Lime—Magnesia Amphibole. 
(Ca, Mg) Si, or rather (Ca Mg?) Si. 
Amianthus, Asbestus, Tremolite, Nephrite. 
Anuanthus—Fleaible Asbestus. 
1. The purest and most flexible amianthus in Scotland—probably in the 
world—is to be found in thin rifts in the diallage rock of Balta in Shetland. 
It occurs at Doo’s Geo, and Muckle Head Geo; chiefly, in both cases, over 
the edge of the cliffs. It is here associated with a peculiar antigoritic allo- 
morph, and a deep green hydrated asbestus. The fibres are not generally over 
three or four inches in length, but they are finer and softer than those of any | 
other locality. They have very slight tenacity ;—when rolled between the 
fingers, they work first into a delicate felt, and ultimately into the smoothest 
and softest conceivable powder. This is absolutely impalpable. 
This variety is not at all suited for the manufacture of incombustible paper ; 
but as a lubricant it would be invaluable ; stuffing-boxes packed with it would 
be as devoid of friction as if the most highly-purified graphite were employed ; 
no talc that I have seen is softer, no French chalk nearly so soft. The colour 
is a very pale watery grey-green. The specific gravity is 2 - 949. 
1°3 grammes yielded— 
Silica, . : ‘ «f2D 
From Alumina, . *005 
730 = Ho" 153 
Alumina, : : : 539 
Ferric Oxide, . 5 : - 388 
Ferrous Oxide, ; : 3° TLL 
Manganous Oxide, . ; *769 
Lime, . . ; LG 
Magnesia, . 22°461 
Potashvare : 4 ; “188 
Sodan uae : : : *692 
Water, . ; : : ee) 

99° 517 
Insoluble silica, 3° 382 per cent. ; was pure. 

