86 THE ROYAL SOCIETY OF CANADA 



The detection of chromium is interesting as suggesting the 

 presence of Daubréeilte, but metallographic examination gave no 

 indications of any foreign material other than graphite. The low- 

 values obtained for sulphur and the high values for the metals are 

 difficult to explain, as the sulphur was determined by the alkali 

 carbonate-nitrate fusion method. It is possible, but unlikely, that 

 the small amount of graphite present exercised a reducing action on 

 the melt, resulting in the formation of alkali sulphides and consequent 

 loss of sulphur as H2S on acidifying with HCl. It is possible also 

 that inclusions of iron or phosphide may have been present. After 

 the analysis had been made it was found that some of the grains of 

 troilite were attracted by a magnet, while others were not. The 

 concentration of phosphide in the neighbourhood of the nodule would 

 lead one to suspect that some may have been mixed with the troilite. 



Analysis 7. — Troilite-graphite intergrowth (PI. XIV, Fig. 20). 



It was thought that Daubréelite might be present in the mixture 

 or that at least a higher percentage of chromium might be found in 

 the troilite associated with the graphite. The results of a partial 

 analysis, as showm below^, failed to confirm this suspicion. 



Fe \ 



m \ 38.26 



Coi 



Cr 0.68 



S 22.35 (Calculated equivalent to 38.94% Fe) 



C 38 .71 (By difference after ignition in oxygen) 



100.00 



Analysis 8. — Apatite (?) embedded in Troilite-graphite nodule. 



While selecting pieces of crushed troilite for analysis a small 

 grain of colourless to white material w^as found embedded partly in 

 the central mass of pure troilite and partly in the troilite graphite 

 mixture (see diagram, page 85). The grain was cylindrical in form, 

 about 3 mm. long and 1 mm. in diameter. Qualitative tests definitely 

 indicated lime and phosphoric acid as the most prominent constituents 

 with a little iron and alumina also. Beryllium was not detected. 

 The refractive indices were determined by E. Poitevin and found to 

 be 1.660 and 1.654. There is little doubt that this was apatite, 

 though perhaps slightly abnormal in composition. 



