ON ANORTHITE FBOM MIYAKEJIMA. 



35 



turbsd or diffused reflection. Hence the measurement of this facial 

 anofle did not g-iye always a satisfactory result. With the clearest 

 piece Avhich I could get, the angle of i^ : M (001 : 010) was found to 

 be 94° 8' and the angle P : il/' (001 : 0Ï0) 85° 51', while the corre- 

 sponding angles of the Anorthite of Vesuvius are 94:° 10' and 85° 50'. 

 The foJlowino" faces have been identified : — 



r = oV (001) 

 M = crA>db (010) 

 T = or.;P (1Ï0) 

 / = cc7V (110) 



z = cc;pS(130) 



/• = ccP;3(130) 

 / = :2'P'cÄ(20l) 

 // = ^,V,^ (201) 



c = 21''àb (021) 



// = 2'/'d6(021) 



m= F' (HI) 



= 1\ (HI) 



i>= p (111) 



h = 4'P2 (241) 



V = 47^,2 (24Î) 



ir == 4/^2 (241) 



u = 2L\ (221) 



X = ,Vr^ (101) 



Some of the ap[)roximate measurements of the important angles are 

 given below, compared with the angles calculated by v. Kohscharow* 

 for the Vesuvian crystal : — 



Kokscharow. 



7" =. 98Vo° 98° 46' 8" 



89 27 2(3 



90 32 34 



142 13 6 



139 48 34 



l) •> o >> /» 



OO O OO 



133 14 12 



II 



y 



y 



y 



y 



y 

 p 



M' = 89 



M = [)()' 



u = 142 V, 



p = 139 7, 



n = 83 V, 



n' = 133^ 



The faL-es t, m, h, v, iv, u, are very rare, x lias been observed in 

 one specimen only as a yery narrow band. 



• Materialien zur Minéralogie Kiisslancls. Bd. IV. 



