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

The bisectrix of the (010) face pole of the two complexes: f

M = + 0.55505 i - 0.73427 £ + 0.39086 k o The mean value of the unit vector resulting in from the measurements of the optical directions and crystallographic ones: f = + 0.55406 i - 0.73322 i_ + 0.39418 k —

o — — In the following the twinning axis is transformed into the system of co-ordinates in which X' = Kj Y* = Mj Z» = Zj fl M + 0.49798 ±* + 0.84825 £» + 0.03938 k' The Goldschmidt values of this: <p = 31.9°, P = 87.75°, i.e. this is a normal twinning law according to (130). The theoretical values: 0

, = 30.20°, P= 90.0°. The optical symmetry axes being transformed into the system of co-ordinates of the first complex: - 0.46711 i' + 0.84910 k» - 0.48181 i» + 0.00625 k' + 0.73569 j.' + 0.54483 k' Eight twin crystal This crystal occurs in the same rock where the fifth twin crystal was found. The measurement data and vector components of the plagioclase shown in Pig. 9. are the following: I. = the (010) cleavage and composition plane in the complex containing the members A, B and C. tLj = 119° hj = 19.5° a' = - 0.24375 i» ~

B

o b» = + 0.88485 i' cl = + 0.39444 i'