1820.] Scientific Intelligence, 71 



Silica 98-75 



Oxide of iron 0'75 



Water 0-25 



99-75 



The bucholzite in its chemical composition approaches very 

 nearly to nepheline, which, according to the analysis of Vau- 

 queUn is composed of 



Silica 46 



Alumina 49 



Lime 2 



Oxide of iron 1 



98 



But as the properties of these two minerals seem to differ 

 materially from each other, it would be premature to unite them, 

 into one species. Indeed further researches appear to be want- 

 ing before confidence can be put in the composition of nephe- 

 line. 



VIII. Andahisite. 



Dr. Brandes has likewise subjected the andalusite of the 

 Tyrol to a chemical analysis. The characters of the specimen 

 analyzed were as follows : 



The principal colours were ash-grey and greyish-white, but in 

 «ome places there were spots of dark-grey and reddish-grey. 

 Fracture uneven, varying from fine granular to splintery. The 

 fragments were indeterminate angular, and pretty sharp-edged. 

 Slightly translucent on the edges. Hard enough to scratch, 

 glass. Exceedingly easily frangible. Not altered when heated 

 alone before the blow-pipe. With calcined borax, it melts 

 readily, and, when cold, assumes the form of a greenish bead. 

 It occurs crystallized in four-sided prisms almost rectangular. 

 The angles could not be determined accurately ; but the measure- 

 ments gave 93° and 87^°. The constituents of this mineral, as 

 found by Dr. Brandes, are as follows : 



Sihca 34-000 



Alumina 55-750 



Oxide of iron 3'375 



Oxide of manganese 0-625 



Potash 2-000 



lime 2-125 



Magnesia 0-375 



Water l-OOO 



90-250 



Were we to disregard all the constituents of this mineral 



