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

o o = - 0.63059 i + 0.52581 j_ + 0.57086 k Between the members A and B there is the Carlsbad law, the adequate' bisectrixes of the o and Y optical symmetry axes include and angle of 0.36°, the vibration direction ß cannot be taken into account. Z

T = - 0.69369 i + 0.00020 j_ + 0.72027 k 1 o Z

T = - 0.69011 i + 0.00094 d + 0.72370 k lc

o The unit vector of the bisectrix: Z

T = - 0.69190 i + 0.00057 A + 0.72199 k o This vector lies to 90.04° from the arithmetical mean of the two neighbouring^p| vibration directions. My , however, lies to 89.83° from Zj , by the vectorial multiplication of them K

T is obtained. 0 o K- = + 0.58032 i + 0.59535 A + 0.55567 k o Between the twin members C and D the Roc Tourné twinning law can be established. The bisectrixes of the optical vibration directions are the following: K

TT = + 0.65707 i - 0.38491 A + 0.64817 k a

o -IIb = + °*

6

5849 i - 0.38320 A + 0.64773 k o K

IT = + 0.65795 i - 0.38200 A + 0.64899 k c

o The sides of the triangle of error are: 0.00°.Converting the arithmetical mean of the three vectors into unit vector: K

IZ = + 0.65784 i - 0.38337 A + 0.64830 k o