54 Graham — Pseudomorphs in McGill University Collection. 



approaches in chemical composition to wilsonite and other 

 pseudomorphs after scapolite, which it further resembles in 

 having a low fusibility and a density of about 2-6 ; indicating 

 that the pinite may here also be an alteration product of scapo- 

 lite. The presence of calcite dispersed in patches throughout 

 the mass would be well in accord with such a replacement. 



It would seem, then, that the original crystal of corundum 

 was first coated with a thin layer of granular black tourmaline ; 

 that the corundum kernel subsequently underwent a pseudo- 

 morphous change to some mineral having cleavages at 90° 

 or nearly 90,° such as scapolite, and that this in turn became 

 altered to pinite. I have not, however, been able to find any 

 description of, or reference to, pseudomorphs of scapolite after 

 corundum. 



The exact locality of the specimen is not known, but it 

 comes from the apatite region of Perth, Ontario, and it is 

 interesting that a cavity in one of the prism faces contains a 

 little transparent apatite of a pale greenish yellow color. 



The pseudomorph is especially remarkable on account of 

 the size, and the sharp outline and regularity of the crystal, in 

 which respects it differs much from the majority of corundum 

 crystals from Canadian localities, these being usually much 

 smaller and not so well developed. 



Chemistry Building, 



McGill University, 

 Montreal. 



