F. D. Adams — Nepheline Syenite in Ontario. 11 



It is in the southeastern portion of this district in the town- 

 ships of Dungannon and Faraday, in the county of Hastings 

 that the nepheline syenite was discovered. 



The mass is crossed by the well known Hastings Road, near 

 the village of Bancroft, and is — roughly speaking — about 

 eighty-five miles in a straight line northwest of Kingston, 

 Ontario. 



The area is a large one but its exact limits have not as yet 

 been determined. It has however been traced in an easterly 

 direction from a point in the township of Faraday, some dis- 

 tance west of Bancroft, to the York River on lots 12 and 13 

 or range XI of the township of Dungannon, a distance in a 

 straight line of over seven miles. It also has a very considera- 

 ble width. 



As occurrences of nepheline syenite are rare, and this is the 

 first one which has been found in the Laurentian system of 

 Canada, and as, moreover, the rock presents a number of strik- 

 ing petrographical peculiarities, it has been thought that a 

 preliminary notice of it at this time would be of interest. 



Mode of occurrence and macroscopical character. — The 

 mass occurs in the Laurentian and is flanked on the south, 

 along a considerable part of its course by crystalline limestone. 

 It is in many places intimately associated with a fine grained 

 reddish biotite granite resembling aplite in appearance and 

 which is apparently intrusive. The nepheline syenite is fre- 

 quently massive in character, but usually possesses a somewhat 

 streaked appearance, in places developing into a distinct folia- 

 tion or gneissic structure, coinciding with that of the associated 

 rocks. On the weathered surface little cavities are occasionally 

 observed which are probably miarolitic druses. It is usually 

 rather coarse grained, but in places becomes very coarse, as at 

 the York River above mentioned, where nepheline individuals 

 two and a half feet across were observed, with feldspar and 

 mica crystals of corresponding size, while individuals one foot 

 in diameter are numerous. On the weathered surface the 

 nepheline and plagioclase which compose the great bulk of the 

 rock can be readily distinguished, the former apparently dis- 

 solving away under the influence of the weather and present- 

 ing smoothly rounded surfaces of a gray color, like those so 

 frequently seen in coarsely crystalline limestone. From these 

 surfaces the plagioclase stands out in white chalk like grains 

 or masses, while the other essential constituents of the rock 

 are also readily recognized. 



Microscopical character. — Under the microscope the essen- 

 tial constituents of the rock are seen to be nepheline and 

 plagioclase, together with either a brown mica or a dark green 

 hornblende. As accessory constituents, seldom absent and in 



