The Chemical Composition of Andradite. 479 



The Chemical Composition of Andradite from 

 Two Localities w Ontario. 



By B. J. Harrington, B.A., Ph.D., McGill College. 



(Presented to the Meeting of the Royal Society cf Canada, 

 May 17th, 1895). 



1. Lutterworth. 



The specimens examined were collected by Dr. F. D. 

 Adams at the '" Paxton Iron Mine," in the township of 

 Lutterworth, Ontario. 1 The magnetite at this locality is 

 associated with a number of other minerals, including 

 garnet, pyroxene, and hornblende. The ore body is also 

 cut by reticulating veins holding quartz, calcite, ortho- 

 clase, pyroxene, scapolite, allanite, etc. The garnet is 

 black in colour, and looks exceedingly like ordinary black 

 tourmaline. It is mostly massive, but also found in crys- 

 tals, which are rhombic dodecahedrons with their edges 

 generally truncated by the tetragonal tris- octahedron 

 ( oo 0, 2 2). Carefully selected material was found 

 to have a specific gravity of 3.813 at 17°C, and gave on 

 analysis the following percentage compositions : — 



Silica 35.68 



Alumina 5.88 



Ferric oxide 23.70 



Ferrous oxide 3.65 



Manganous oxide 0.81 



Lime 29.64 



Magnesia 0.35 



Loss on ignition 28 



99.99 



The mineral was specially examined for titanium, but 

 no trace found. 



1 See Report of the Geological Survey of Canada, Vol. VI., 1891-92-93, Part J, by 

 Dr. Adams, 



