314 DEPARTMENT OF THE INTERIOR 



2 GEORGE V, A. 1912 



The calculated norm is: — 



Orthoclase.. . ." 24-46 



Albite 15-20 



Nephelite 3-69 



Anorthite _ 18-90 



Diopside 16-68 



Olivine 5-97 



Ilmenite 1-36 



Magnetite 3-94 



Apatite 1-24 



Water and C0 2 ., 9-14 



100-58 



According to the Norm classification the rock enters the sodipotassic sub- 

 rang, shoshonose, of the alkalioalcic rang, andase, in the dosalane order, ger- 

 manare. Chemically it is nearer minette than a typical kersantite, but, by 

 the older classification, the character of the feldspar places the rock in the 

 kersantites. 



Camptonite. — Only one occurrence of camptonite is known as a result 

 of field study in the Boundary belt .across the Selkirks. This rock, which 

 microscopic study shows to conform well with the type camptonite, forms a 

 wide but very poorly exposed dike cutting the Pend D'Oreille phyllite on the 

 south side of the Pend D'Oreille river about 1,900 yards east of Waneta. 



Odinite. — A half mile farther up the river and on the same bank, the phyl- 

 lite is cut by a six-inch dike of a rock which appears to represent another 

 occurrence of typical odinite as described by Eosenbusoh in his last edition 

 of the Mikroskopische Physiographie der Massigen Gesteine. This lamprophyre 

 is a dark greenish-gray, compact rock with conspicuous though small phenocrysts 

 of augite and others of labradorite. The microscope shows these to be embedded 

 in a microcrystalline ground-mass composed essentially of very many minute 

 prisms of hornblende, feldspar microlites, and less abundant granules of augite. 

 A detailed description of this one thin dike, though composed of a relatively 

 rare species of lamprophyre, is scarcely warranted in the present report. 



Aplitic axd Acid Apophysal Dikes. 



Practically all of the granitic bodies in the Selkirks where crossed by the 

 Boundary belt have sent tongues or apophyses into their respective country- 

 rocks. These dikes show the familiar variation from quartz-feldspar aplites 

 to the aschistic porphyries corresponding to the different types of plu tonics. 

 Other sills and dikes occur at distances too great to be regarded as necessarily 

 apophyses from any visible stock or batholith, and in some cases it is not 

 possible to determine whether these detached acid eruptives represent distinct 

 periods of eruption. None of the bodies seems to demand special description. 

 One of the dikes is cut by augite minette and by the analyzed hornblende- 

 augite minette which occur on the western bank of the Columbia river about 



