186 THE ROYAL SOCIETY OF CANADA 



of erosion, it is now represented chiefly by the lava flows, which are 

 predominantly basaltic. The basalt passes transitionally into vesicu- 

 lar and amygdaloidal types, the amygdules being in many places well 

 banded but pale coloured chalcedony. Zeolites, a green chloritic 

 mineral, quartz, and calcite (the latter intergrown with chalcedony) 

 also fill vesicles.^ 



In the railway cut where the ferrierite was found, the rock is a 

 massive olivine-basalt. Where fresh, this rock is nearly black in 

 colour, and fine grained, but with a distinctly porphyritic structure. 

 A thin section of a very fresh specimen was examined and showed well 

 developed phenocrysts of plagioclase feldspar, pale brownish-green 

 pyroxene, and colourless olivine, the latter only very slightly altered 

 to serpentine. A fair number of grains of magnetite are present, 

 and all these minerals are distributed through a finely crystalline 

 ground-mass, with no apparent tendency towards a fluidal arrange- 

 ment. 



Fractures traversing the basalt are filled with seams, or veins, of 

 pale coloured, translucent chalcedony, and in the vicinity of these the 

 rock is very much decomposed, soft, and crumbling. The seams vary 

 from mere films to veins several inches in width, but they are usually 

 quite narrow. The ferrierite occurs within the chalcedony, which 

 completely or partially encloses the spherical aggregates of the mineral. 

 Subsequently to the formation of the chalcedony and ferrierite, white 

 coarsely crystalline calcite has been deposited in the veins. Many 

 of the ferrierite aggregates are thus partially enclosed in calcite, and 

 by dissolving the latter in dilute acid, their surfaces may be freed, 

 when the outer ends of the crystals are found to exhibit terminal 

 faces. In the best specimens collected, the spheres have a radius 

 of three-eighths of an inch, but for the most part they are smaller 

 than this. 



In addition to the new mineral, Dr. Ferrier reports the occurrence 

 at this locality of agate, and also chalcedony géodes lined with crystals 

 of amethyst, as well as with ordinary quartz. Finely developed flat 

 rhombohedral crystals of calcite are, in some cases, implanted on the 

 quartz, and in one specimen crystals of the latter mineral are coated 

 with tufts of minute rutile crystals. These géodes are sometimes over 

 six inches in diameter. Some of the smaller ones, measuring two or 

 three inches in diameter, are completely filled with coarsely crystalline 

 calcite, with a comparatively narrow marginal zone of banded pale 

 chalcedony, between which and the calcite there may be some quartz. 



1 See Summary Report, Geological Survey, 1912, p. 142: Geology of the Thomp- 

 son River Valley below Kamloops Lake, B.C., by Chas. W. Drysdale. 



