Evans and Bancroft — Gedrite in Canada. 



511 



from the finest dust, it was then placed on a sieve of 100 

 meshes to the inch, and that portion which passed through the 

 latter sieve was discarded. The material was then submitted 

 to the action of a Wetherill Magnetic Separator provided 

 with two pair of magnets, the first of which were placed one 

 quarter of an inch apart while the second set were 5/16ths 

 of an inch apart. It was found that "8 amperes removed 

 the magnetite and a little ilmenite, while with a current of 3 

 amperes the rest of the ilmenite, the rutile, some garnet and 

 some anthophyllite were withdrawn. The current was then 

 raised to 15 amperes, which removed the remainder of the 

 anthophyllite and the garnet with most of the biotite, the 

 tailings consisting of cordierite, quartz and a little biotite. 

 In order to complete the separation recourse was had to heavy 

 solutions. By means of Klein's solution the garnet was 

 removed. Iodide of methylene was then employed, which 

 when diluted with a few drops of benzol was of such a specific 

 gravity that the biotite floated while the anthophyllite sank. 

 This latter, however, was seen, when examined under the 

 microscope, to still contain a few composite grains of feldspar 

 or garnet with a little black iron ore. The powder was 

 accordingly placed under a lens of low power and the foreign 

 material removed by means of a fine needle. Perfectly pure 

 anthophillite was thus secured. 



In the analysis which was made by N. Norton Evans all 

 the determinations were made in duplicate with the exception 

 of those of water and the alkalis. The mean of the analysis 

 of the air-dried powder is given below. An analysis of the 

 original gedrite from the valley of Heas by Pisani is pre- 

 sented for purposes of comparison. 



SiO 



Tot 



vnship c 

 Ont. ( 



44-32 



16-04 

 2'80 



16-88 

 0-09 

 0-77 



15-95 

 1-31 

 1-86 



f Harcourt 

 Evans) 

 Ratio 



•734 

 •156 

 •017 

 •235 

 •001 

 •013 

 •395 

 •073 

 •024 



is -741: 



Si0 2 is 



} 



Valley of He"as, ne 

 Geclres. (Pisani) 



43-58 



41 O 









17-07 



FeO, .... 





-- 









FeO 





15-96 



MnO 



CaO 





0-75 



M^O ... 







18-30 



HO 







3-92 



K 2 "0 and N 



a. 2 



EC 



of 



•734, 

 173: 



or very 

 •734, or 





The ratio of 

 and the ratio 



.00-02 



I : Si0 2 

 R 2 3 : 



99-58 



nearly 1 

 almost 1 



