508 PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 
Actynolite. 
Magnesia, Lime, Iron—Amphibole. 
(Ca Mg Fe) Si. 
From Rocks of Hornblendic Geiss. 
"~ 8. Found at the well-known locality of the banks of Nidister, Hillswick, 
Shetland. The exact spot is just where the low banks, trending nearly south, 
are suddenly met by a cliff of several times their height, which lies at right 
angles to their course. There is, if not a junction here, much vein confusion ; 
and among these veins one of about two feet in thickness, composed entirely of 
long tortuous crystals of glassy actynolite, lying in silvery white tale and soft 
chlorite, strikes with a north-easterly course out of the bank. This vein has 
one of serpentine on its north side, and another of anthophyllite on its south. 
It seems to pass into chlorite and Biotite, where it is covered by the shingle 
of the beach. The specimens of this actynolite, though exceedingly fragile 
from the softness of their matrix, and from their own brittleness, are the finest 
in Scotland. The crystals are well formed, though not terminated ; they are 
semi-transparent, highly lustrous, and bright green; their angle is 124° 29’; 
their specific gravity, 2 ° 993. 
On 1° 3 grammes— 
Silica, 4 : ay bi 
From Alumina, . - 004 
15 = Boe 
Alumina, . f pee Gaus 
Ferric Oxide, . ; : * 994 
Ferrous Oxide, . : te SSE 
Manganous Oxide, . : - 307 
Lime, ; ‘ : . dO S8t 
Magnesia, . é : . 23°307 
Potash, : ; So) ea 
Soda, ; : . me oor 
Water, 2-898 
100 : 072 
Insoluble silica, 1-958; loss in bath, - 266 per cent. ; possible impurities, 
chlorite and tale. 

