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

Ztt = - 0.55491 i + 0.73739 i + 0.33514 k llc

o The values of the bisectrixes hardly deviate from each other: Kp = - 0.61202 i - 0.65165 £ + 0.44782 k o Computing by vectorial multiplication from the directions M-jand Z-r yy : My X Zy o o MII x £n o o = + 0.60425 i - 0.67517 £ + 0.42310 k = + 0.20307 i - 0.32972 j_ + 0.92199 k Between the twin members B and E the twinning axis is denoted by the letter f

. f = + 0.80587 1 + 0.32006 i + 0.49813 k o f

b = + 0.83809 i + 0.27666 j_ + 0.47034 k 0 f = + 0.80806 i + O.32457 j + 0.49161 k c

o The two ß are close to each other, thus they are slightly inaccurate. The mean value computed from the directions a and Y : f

0 = + 0.80697 i + O.32232 £ + 0.49487 k The bisectrix of the face normal (010) of the two complexes: f

M = + 0.80201 i + 0.34091 i + 0.49045 k 0 The values obtained from the optical directions are used. The transformed values of the optical vibration directions of the twin member E: ag = - 0.24672 i" - 0.52233 £" + O.8I5O6 k

M