I3ö 



From a little crystal group consisting of several individuals 

 grown together in parallel position 1 succeeded in producing a 

 prism, one side of Avhich is parallel to the first pinacoid, and 

 the refracting edge to the c-axis. With the light falling at right 

 angles to the said side 1 measured in this prism the refraction 

 of the two rays vibrating in the plane of the optic axes. The 

 indices calculated from the measurements are: 



Red 



Yellow 



Green 



a = 1,7320 



1,7431 



1 ,7580 



;- = 1,7785 



1,7876 



1 ,8025 



J— a = 0,0465 



0,0445 



0,0445 



A prism for the determination of ß could not be produced. 



In a section perpendicular to the first mean line, and conse- 

 quently parallel to the second pinacoid, the angle between the 

 optic axes was measured in air. The result obtained for light 

 of medium wave-length was 



IE = 72°. 



Lorenzenite scratches adularia with difficulty. Its hardness 

 is thus a little above (5. The mineral has a distinct cleavage 

 parallel to the faces of the form n. Whether there is any other 

 cleavage in the zone of the vertical axis, cannot be decided. 

 When the crystals are crushed , they separate into splinters 

 whose longitudinal direction is parallel to the said zone. 



Before the blowpipe lorenzenite fuses easily to a black 

 globule. With salt of phosphorus a silica skeleton is obtained. 

 The mineral is decomposed by hydrofluoric acid, but by no 

 other acids. 



By weighing in benzole the specific gravity has been found 

 to be 3,42. This determination has been made by R. Mau- 

 zelius, who has also performed the analysis. In the analysis 

 0,5727 gr. of pure material was used. The values obtained are 

 as follows : 



