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

The twinning axis T is transformed into the systems Z' Y' Z* and X" Y" Z". X' = - Kj Y' = - Mj Z» = Zj - O.51213 i* + O.OO365 k' + O.50347 i" + O.OO365 k

n The Goldschmidt-values: <p= 120. 6° p » = 89.8° Between the members C and E there is a twinning law according to (llO), resp. after the inversion centre according to (llO). 0

n = 300.4° P" = 89*8° The Goldschmidt values to the (1Î0) face interpolated to 60 per cent anortite: <p = 118.93° p= 90° The transformed value is T' —o T* = + 0.85873 1* —0 — T" = - 0.86385 i" Second twin crystal The plagioclase twin crystal demonstrated in Pig. 3. derives from the sample marked by P.5.b. Its place of sampling and the quality of the rock is the same than those of the former one. The anortite content of the twin crystal shown in Pig. 3. is 65 per cent, its measurement data are as follows: I. = the (OlO) cleavage and composition plane of the first complex containing the members A and B. II. = the (010) cleavage and composition plane of the second complex containing the members C,, D and E. 30