Dr. Nagy I. Zoltán szerk.: Fragmenta Mineralogica Et Palaentologica 4. 1973. (Budapest, 1973)

Twin member P: *

C = 135.5° h

c = 11.3° =- 0.68733 i - 0.69943 j. + 0.19595 k n

b = 227° h

b = 7.1 b

p = + 0.72453 i - 0.67564 j. + 0.13629 k o a

p = fc

F X b o L o o = + 0.03706 i + 0.22841 j. + 0.97115 k A and B: Albite twin (Mj) D and E

: Carlsbad twin (Zjj) B and C: Carlsbad twin (Z,) E and P: Albite twin (M-J-J) A and C: Roc Tourné twin (K^) D and P: Roc Tourné twin (KJJ) Bisectrixes of the optical directions of A and B: M

T = - 0.77825 i + 0.57932 A + 0.24231 k "

la

o -lb = " °77479 i + °«57943 i + 0.25289 k o M

T = - 0.78451 i + 0.56551 A + 0.25448 k lc

o Arithmetical mean is computed which includes an angle of 90° with the Carlsbad twinning axis. = - 0.77918 i + 0.57475 J. + 0.24989 k o The bisectrixes of the optical vibration directions of the members B and C result in the Carlsbad twinning axis. Z

Ia = - 0.02467 i - 0.41911 A + 0.90759 k Z = - 0.01503 i - 0.42259 i + 0.90620 k o Z

T = - 0.02494 i - 0.42635 A + 0.90421 k ic

o