MISCELLANEOUS MINERALS. ? II 



Mr. Richardson informs me that it occurs in a dyke of from one to 

 two feet thick, dipping northward at an angle of about 50°, and cutting 

 through flat massive beds of Potsdam sandstone. That at the time of 

 his visit Mr. Trottier had excavated about twenty feet in depth and 

 the same in length, the produce of which appeared to he about two 

 tons. It was stated that at the depth of twenty feet, the thickness 

 appeared to be increasing, inasmuch, however, as there were several feet 

 of water in the excavation, Mr. Eichardson had no opportunity of 

 satisfying himself on this point. The sample received was in the form 

 of compact friable masses, with a greasy feel, and fine earthy texture. 

 Colour light brownish-yellow mottled with white. Adheres to the 

 tongue. Forms with water an exceedingly plastic paste. 



After drying at 100° C, its composition was found to be as follows : 



Silica 32.009 



Alumina 29.907 



Ferric oxide 14.023 



Chromic oxide 0.554 



Titanic acid 9.558 



Lime 0.41 1 



Magnesia 0.247 



Potash -. 



Soda } Traces 



Water (direct estimation). . 13 005 



99.714 

 All the iron has been calculated as ferric oxide, the amount present 

 as ferrous oxide not having been determined. 



On carefully washing a large quantity of this clay, there ultimately 

 remained, mixed with a little of the coarse material, a very small 

 quantity of a heavy black granular powder which, upon examination, 

 was found to consist, for the greater part, of chromite ; a small quan- 

 tity of titanic acid was also detected in this powder ; it was not, how- 

 ever, satisfactorily determined if this was present in the form of 

 Ilmenite or no. 



In order to test its refractory quality, some of the clay was moulded 

 into the form of minature bricks, the edges of which were left as sharp 

 as possible ; these having been carefully dried, first by exposure to 

 the atmosphere and then to a temperature of 100° C, were subse- 

 quently inserted in a covered crucible, and this latter placed in an air- 

 furnace, the temperature of which was gradually raised until at the 

 expiration of about an hour, an incipinent white heat had been 

 obtained, at which temperature it was maintained for an additional 

 hour. On examining the contents of the crucible after cooling, it was 

 found that the edges of the bricks remained perfectly in tact, showing- 



Analysis of 



kaolin. 



