126. 



zeolites, chiefly levynite, chabazite, thomsonite and stilbite. 

 Only one zeolite is found, as a rule, in each cavity, but, in 

 one case, thomsonite was found on crystals of levynite. The 

 length of the latter crystals is 1 — 2™™; the form varies some- 

 what. In some cavities they are thin and plate-like, in others 

 rather thick. The form comes close to the ordinary levynite 

 form with c{00l}, r{loTl} and s{022l}. Penetration-twins 

 twinned about с (OÜOl) are almost always found, so that 

 r{l01l} is only developed in the re-entrant angles. 



Measurements of the better-developed crystals of the thicker 

 type reveal a circumstance which is probably also to be noticed 

 in other levynite crystals , but which is here very marked. 

 From the positions where the two rhombohedra should be 

 situated no reflex, or hardly any, is seen, but, on the other 

 hand, reflexes appear from two scalenohedra which are situated 

 not very far from the rhombohedral faces. Owing to the stri- 

 ation, the angles vary considerably, but the forms can, with fair 

 certainty, be determined as being two new ones ?; (2 . 10 . 12 . l) 

 and w{l0.2. 12. 11.} The faces s{022l} andr{]On} are 

 very small and give only very feeble reflexes. The axial-ratio 

 generally employed for levynite, namely с = 0"8357 (Haidingee) 

 is not apphcable to the crystals from this locality, for which 

 с = 0*8010i has been calculated. 



The following angles have been measured: 









Average 

 value 



Variation 



Number 

 of meas- 

 urements 



Calcul- 

 ated 

 value 



z:c =^ (10n):(0001) 







= 42°46' 



42°42'— 42°54' 



5 





s:c =(0221): (GOOD 







= 61°28' 



60°49'— 61°53' 



3 



61°36'i 



r:s =(1011): (0221) 







= 49°12' 





1 



49°37'J 



u:c = (10.2.12.11) 



(0001) 





= 43° 6' 



42°55'— 43°15' 



4 



43° 7' 



w:r=(10.2.12.11) 



(loTl) 





= 6°14' 





1 



6° 7' 



v.c = (2.10.12.7 ) 



(0001) 





= 55°42' 



55°26'— 56°25' 



4 



55°48' 



v:u= (2.10.12.7 ) 



(10.2.1 



2.11) 



= 33°50' 



33^^20'— 34° 15' 



3 



33°55'f 



As will be seen from the indices, the scalenohedral faces 

 V and и are both situated in the zone rs == {lOÏl, 022 1 }. 



к I 



