Ransomr. I 



Lawsonite. 



303 



m : m = HO : Ho = 67 16', and 

 d\d — 0\\ : 01 1 = 72 53.5'. 



The faces of the brachydome joiij are marked by a strong 

 striation parallel with the basal edges which renders it difficult to 

 secure good reflections. These striations are present on the very 

 smallest crystals that could be handled, and cause multiple and 

 blurred signals in the goniometer. In the following table of meas- 

 urements the larger variations in the observed angles must be laid 

 to this cause, and to the difficulty of deciding just which one of a 

 series of images is the significant one for the face. The faces of the 

 prisms, { no] are also striated parallel with the basal edges, but less 

 strongly than the dome faces, so that the readings are not so much 

 interfered with. 



TABLE OF ANGULAR MEASUREMENTS OF LAWSONITE. 



No. of 

 Crystal. 



Angle. 



v. & 

 E 



°^ 

 ■ . rt 



Hi 



M ean. 



Extremes. 



Calculat'd 

 Angle. 



Remarks. 



I 



d: 



d- 



- on : 



01 1 



5 



72° 48.S' 



72°4S / — 72°5i' 







Three signals on each 























face. Read middle 



4 







( < 





5 



72° 53' 



7 2°47 / -72°56 / 







One signal rather ill- 























defined. 



11 







1 1 





5 



72° 19. S' 



/2 1 / — 72 22 







Signals faint. 



12 











2 



72° 53-5' 



72 o 52 /_ 72 c 56 / 







Trains of signals. Read 























first and hrightest. 



13 







1 1 





3 



72° 45' 



72° 45 -72° 45' 







Trains of signals. Read 























first and brightest. 



18 











3 



72° 54-4' 



72°54 / — 72 55 







Double signals. Took 























mean of both. 



18 











2 



72° 53-5' 



72° 53 / -72°54 / 







Double signals. Read 























brightest. 



8 



m 



m 



= 1 10 : 



1 1 



5 



67° 16' 



67° 16'— 67° 1 6' 







Excellent signals. 



11 



d 



m 



= 011 



: no 



3 



70° 52 6' 



7 o°5o / -7o 55 / 



70° 



47-4' 



Signals blurred by stri- 























ations. 



6 



d' 



: m 



= 041 



:no 



3 



58° 1 1.7' 



5S° 11' — 5S 12' 



5S° 



21.3' 



jood, clear signals. 



6 



d 



d' 



= 01 1 



: 041 



3 



34° 43-3' 



34° 43'— 34° 44' 



34° 52.2' 



Good, clear signals. 



10 



m 



: 



= 110 



: 001 



5 



90° 0' 



89° 59'— 9<a° 3' 



90° 



0' 





20 



: 



d f 



= 001 



: 041 



1 



71° 15' 





7i° 



i8 / 



Angle observed by Pa- 























lache. 



2 1 



d' 



: m 



— 041 



: 110 





58° 20' 





58° 21.3' 



Angle observed by Pa- 























lache. 



