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

•E - 0.88928 i" + 0.45678 £" + 0.02455 k" o c" = + 0.38560 i" + 0.72111 j" + 0.57733 k" _E

o _ The transformed values are valid in the following system of coordinates : X» = - Kj Y* = Mj Z» = Z

I

_

II X" = - K

i:r Y" = Transformed values of the twinning axis f: f = - 0.49583 i' - 0.86823 A' + 0.01843 k» —

o — **• — f" = + 0.51386 i" + 0.85771 j" + 0.01843 k" —

o — — The Goldschmidt values in the system I.

: 209.73° P= 88.93° in the system II. : 30.91° P

TT

= 88.93° Goldschmidt values of the (130) face normal interpolated to an anortite content of 85 per cent : 0 = 30.25° p = 90° Consequently, between the members B and E there is a twinning law according to (130).(Controlled by first-type Euler angles.) Fourth twin crystal Mark of sample: Szp.8.A. The rock is the same than in case of the third twin crystal. The plagioclase shown in Fig. 5. consists of three groups of Albite, Carlsbad and Roc Tourne twins, but only two of them