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

sequently it corresponds to the (Ï10) face and to the (110) face according to the inversion centre. The 0 value of the latter is 60.05° in contrary to the theoretical 60.01° which is the interpolated angle value of 80 per cent anortite. Instead of the theoretical 90.00° the P angle is 90.05°. Sixth twin crystal Sign of the rock sample: Z 6. Place of sampling: the agglomerate occurring in the right side of the street of west-east direction starting from the railway station in the village Zebegeny. It is a light-grey rock, its texture is porphyric-microlitic. In the porphyric feldspars there is a lot of glass inclusions. The rock contains small quantity of pyroxene and has somewhat higher decomposed amphiboles. The measurement data and unit vectors of the grain shown in Pig. 7. are the following: I. = the (OlO) cleavage and composition plane of the complex containing the members A and B. n, = 208° hj = 24.5° II. = the (010) plane of the second complex containing the members C and D. n

II = 3435 h

II = « 1. = the (OOl) cleavage plane Pig. 7. of the member B. n

1 = 110.5° \ = 25

l St ül! I - 0.84891 i - 0.31740 ^ + 0.42262 k + 0.42720 i - 0.80345 j. + 0.41469 k + 0.27434 i + 0.92615 j_ + 0.25882 k