ADDITIONAL CHEMICAL EXAMINATIONS. 



603 



Alumina, soluble in HC1, ......... 3-3 



Oxide of iron, " " . . . . . . . . 1-2 



Magnesia, " " . . . . . . . . . 0-73 



Manganese, " " . . . . . . . . -9 



Potash, ........... -7 



Soda, ........... 1-1 



Water, ........... 9- 



This mineral does not agree exactly in composition with any mineral of which I have seen an analysis. 

 It comes nearest in its composition to a variety of Phillipsite from Iceland, analyzed by Damour, except 

 that magnesia replaces the lime in Phillipsite, and this mineral would therefore bo a magnesian Har- 

 motomo. 



It differs, too, in its degree of hardness, from the Phillipsite, or lime Harmotomc. 



The magnesian Harmotome from Minnesota decrepitates before the blow-pipe, and fuses to a nearly 

 colourless blebby glass, with a faint tinge of yellow. 



The analysis of this mineral gives a slight excess, which ought probably to be deducted from the alumina, 

 which being bulky was very difficult to wash clean. 



It exists in the cells of the amygdaloids of Kettle River, in its nascent state, and could be spread 

 with a knife, just like the saponite mentioned by Alger, who states that some of the miners of Brucks- 

 veden tried to eat it as a substitute for butter. 



ANALYSES OP OTHER MINERALS FROM THE NORTH SHORE OP LAKE SUPERIOR. 



An analysis of a radiated mineral, of a wavy lustre and silky fibrous structure, in the cells of the 

 amygdaloid No. 371 of Dr. Norwood's collection, from the northwest shore of Lake Superior, probably 

 a variety of mesole, gave the following results : — 



Water, ....... 



H = 



12 



Silica, ....... 



Si = 



43 



Alumina, ....... 



Al = 



25 



Lime, ....... 



Ca = 



O 



Magnesia (with a trace of Mn), .... 



Mg = 



10 



Oxide of iron and matter insoluble in potash, 



Fe = 



o 



Alkalies, ....... 





4 







99 



The analyses of different varieties give considerable variation in the amount of lime and magnesia, as 

 if they replaced one another in the mineral in question. 



The following is an analysis of a light-red, foliated mineral, having a pearly lustre encrusting argil- 

 laceous iron ore, collected by Dr. Norwood, on the northwest shore of Lake Superior : 



Water, ....... 



H 



= 14-000 





r si 



= 55-200 



Insoluble silicates of alumina, lime, and alkalies, 7734, 



J Al 



= 10-400 





J Ca 



= 5-1S4 





^ Alk 



= 6-556 



Oxide of iron, ...... 





a trace. 



Alumina, dissolved by IIC1, ..... 



Al 



= 7-040 



Alkalies, with a trace of Mn, .... 





1-600 



Loss, 





0002 







100-000 



The silica in this mineral agrees best with stilbite, but the water is more nearly that existing in Heu- 

 landite ; the lime is nearly 2 per cent, less than in stilbite, and the alkali 4 to 6 per cent, in excess, but 



