Canada 
Geological Survey 
Victoria Memorial Museum 
BULLETIN No. 1 
XII . — Prehnite from Adams Sound , Admiralty Inlet, Baffin 
Island, Franklin. 
By Robt. A. A. Johnston. 
The material which furnished the subject of this article was 
collected by Mr. Arthur English while engaged as prospector 
on the expedition of 1910-1911 of the Canadian Government 
steamer Arctic under the direction of Captain J. E. Bernier. 
The locality is given as near the head of Adams sound, which 
would make its position as about 73° 12' north latitude and 
82 30' west longitude. And from information gained from a 
letter written by Mr. English to Dr, A. P. Low, Deputy Minister 
of Mines, in which he gives a summary of his observations upon 
the geological features of the country, it would appear that 
near the head of the sound extensive beds of shale are exposed. 
These shales are impregnated to a greater or less extent with 
iron pyrites and copper pyrites; the pyritous minerals occur 
in the form of flattened nodular concretions and thin scales 
and are particularly abundant along the contact with gabbroid 
intrusives by which the shales are extensively invaded; these 
intrusives often take the form of dykes of large proportions, 
ranging from 1 foot to 30 feet or 40 feet in width. In 
the neighbourhood of these intrusives the strata are traversed 
by numbers of vertical veins of quartz and calcite, in which 
galena and pyrite and even fine particles of native gold have 
sometimes been observed. And it is presumably from one of 
these quartz-calcite veins that the mineral under consideration 
has been obtained. 
