ORDER VI. PARATOMOUS KOU PHONE-SPAR. 231 



OBSERVATIONS. 



1. The dimensions of the crystalline forms of this spe- 

 cies have not yet been ascertained with sufficient exact- 

 ness. As a point of comparison, the isosceles pyramid of 

 121 58', 86 36', given by HAUY, may be useful, although 

 it supposes the prism P + os to be a rectangular four-sided 

 prism, like that produced by the enlargement of o and q. 

 Mr PHILLIPS finds the edge replaced by the horizontal 

 prism Pr to be = 119 4', and the angle of that prism it- 

 self = 110 26', from which two data the other terminal 

 edge of P would follow 121 6'; 



2. According to KLAPROTH, the paratomous Kouphone- 

 spar consists of 



Silica 49-00. 



Alumina 16-00. 



Baryta 18-00. 



Water 15-00. 



Alone upon charcoal it melts, without intumescence, into a 

 clear globule. It phosphoresces with a yellow light, and 

 is not easily acted upon by acids. 



3. Paratomous Kouphone-spar occurs pretty frequently 

 in metalliferous veins, but is found also in vesicular cavi- 

 ties of amygdaloidal rocks, like most other species of the 

 present genus. The crystallised varieties in cruciform 

 twins from Andreasberg in the Hartz, and in simple crys- 

 tals from Strontian hi Scotland, are very generally known. 

 They occur in metalliferous veins, traversing greywacke- 

 rocks, accompanied by rhombohedral Lime-haloide, hexa- 

 hedral Lead-glance, and in the first locality, also by pris- 

 matoidal Kouphone-spar. This species is likewise met 

 with in veins traversing mica-slate and hornblende-slate, 

 with ores of silver, &c. 



3. Besides Andreasberg and Strontian, veins are the re- 

 positories of the present species at Kongsberg in Norway. 

 It is very frequent in amygdaloid, as in various places in 

 Scotland ; at Oberstein in Deuxponts, where it is found in 

 the agate balls ; in Baden ; near Engelhaus and Buchau in 

 Bohemia, and in the vicinity of Mount Vesuvius. 



