70 Scientific Intelligence. [July, 



approach in the composition of meionite to scapoHte and preh- 

 nite. As the specimen subjected to examination was not abso- 

 lutely pure, it would be unsafe to attempt from the preceding 

 numbers to deduce the constitution of the mineral. — (Schweig- 

 ger's Journal, xxv. 36.) 



VII. Bucholzite. 



This is the name by which Dr. Brandes has thought proper to 

 distinguish a mineral similar to that formerly described by Werner 

 under the name oi fibrous quartz. It occurs in alumslate, in Voigt- 

 land, near Hartmannsdorf, and at Wiesenbad in a gangue of ame- 

 thyst. The mineral which Brandes subjected to analysis, however, 

 came from the Tyrol, and though it resembles fibrous quartz in its 

 appearance, Ave have no evidence that it agrees with it in its 

 constitution. It will be requisite, therefore, to give the descrip- 

 tion of the bucholzite of Brandes, and not to confound it with 

 the fibrous quartz of Werner till it has been determined by actual 

 analysis that both are composed of the same constituents. 



The colour is a mixture of white and black in spots. Lustre 

 glistening, and the kind of lustre, is waxy, pearly, and glassy. 

 The principal fracture is fibrous, and most remarkably so in the 

 black spots. In the grey and white-coloured spots, the texture 

 is often with difficulty recognisable. The cross fracture displays 

 here and there a conchoidal fracture. In some cases there is a 

 tendency to the foliated fracture, and the cleavage indicates in 

 these cases an analogy to felspar. The fragments are wedge- 

 shaped, sometimes sharp-edged, and sometimes not particularly 

 so. When in thin fragments it is weakly translucent, and this is 

 particularly the case in the white spots. It is hard enough to 

 scratch glass ; bat is itself scratched by quartz. The result of 

 Brandes's analysis of this mineral, which it seems unnecessary to 

 specify, as it differed in nothing from the usual mode of analysis, 

 gives its constituents as follows : 



Sihca 46-0 



Alumina 50*0 



Oxide of iron 2'5 



Potash 1-5 



100-0 



From the variation in the colour of this mineral, it is probable 

 that the oxide of iron is merely accidentally present, and that it 

 does not enter as a chemical constituent of the mineral. It 

 seems, therefore, to be in reality a neutral silicate of alumina 

 mixed, or united, with a very small proportion of sihcaLe of 

 potash. 



Though I have mentioned fibrous quartz as similar to buchol- 

 zite, there seems no reason to doubt that it is in reality a differ- 

 ent mineral ; for Mr. Zellner subjected the quartz to an analysis 

 (Gilbert's Annalen for 1818, p. 182), and found it composed of 



