1870.] HUNT — ON NORITE OR LABRADORITE ROCK. 37 



suggested tlie application of the labradorite rOcks of Essex County 

 as a substitute for marble (pages 29, 418). An ornamental vase 

 of the same rock, turned in a lathe with the aid of a black diamond, 

 has been in the Museum of the Geological Survey of Canada 

 since 1856. 



Of the collection of norites from Norway the specimens from 

 Sogudal and Egersund presented fine varieties of grayish or 

 browuish violet tints, while a dark violet norite came from Kra- 

 geroe, and also from the islands of Langoe and Gomoe, and a 

 white granular variety from the gulf of Laerdal in the diocese of 

 Bergen. 



It is only in rare cases that the cleavable feldspar of these 

 norites exhibits the peculiar opalescence which distinguishes the 

 finer labradorite found in some parts of the coast of Labrador. 

 Opalescent varieties of this feldspar are, however, occasionally 

 met with in the area near to Montreal and in northern New York. 

 In the Paris Exhibition of 1867 there were exhibited from Rus- 

 sia, large polished tables of a beautiful violet colored granitoid 

 norite, portions of which exhibited a fine opalescence. This rock, 

 I was informed, comes from a mountain mass in the Government 

 of Kiew, but of its geognostical relations I am ignorant. 



These peculiar labradorite rocks, presenting a great similarity 

 in mineralogical and lithological character, have now been observed 

 in Essex County, New York, and through Canada, at intervals, 

 from the shore of Lake Huron to the coast of Labrador. They 

 are again met with in southern New Brunswick, in the Isle of 

 Skye, in Norway, and in south-western Russia, and in nearly all of 

 these localities are known to occur in contact with and apparently 

 reposing, like a newer formation, upon the ancient Lauren tian 

 gneiss. Geikie in his memoir on the geology of a part of Skye,^'^ 

 appears to include the norites or hypersthenites of that island with 

 certain syenites and greenstones, which he describes as not 

 intrusive, though eruptive after the manner of granites (loc. cit. 

 p. 11-14). The hypersthenites are represented in his map as 

 occurring to the west of Loch Slapin. Specimens in my possession 

 from Loch Scavig, a little further west, and others in MacCul- 

 loch's collection from that vicinity, are, however, identical with 

 the North American norites, whose stratified character is undoubt- 

 ed. I called attention to these resemblances in the Dublin 



Quar. Jour. Geol. Soc , xiv., p. 1. 



