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

1 = - 0.60625 i - 0.50746 i + 0.61232 k "

a

o l

b = - 0.61300 i - 0.5Q702 j_ + 0.60593 k o 1 = - 0.61077 i - 0.50196 A + 0.61238 k c

o The sides of the triangle of error are: between the bisectrixes QiJ andQißTj 0.63°, betweenrn

a

~J and£n

Y

*J 0.45°, and between £n^j and[n

y

] 0.55°. Converting the arithmetical mean into unit vector: 1 = - 0;61001 i - 0.50549 A + 0.61022 k —

o — — The bisectrix of the (010) face normal of the two complexes: 1

M = - 0.61118 i - 0.51004 X + 0.60524 k o These two vectors lie to 0.36 from each other, i.e. the deviation is rather small, in the further compution the optical direction will be used. The values of the transformed vectors are valid in the following system of co-ordinates: X' = Kj Y' = Mj Z» = Zj The transformed value of the optical vibration directions of the member C: a» = - 0.29656 i» - 0.51800 j_» + 0.79995 k» o b» = + 0.87163 i' + 0.49010 j_' + 0.00353 k' o c' = + 0.39101 i* + 0.70062 A* + 0.60006 k» -°o Transformed value of the twinning axis: 1» = - 0.86643 i' - 0.49926 + 0.00015 k» Its Goldschmidt

's 9 value is 240.05°, Pvalue is 89.95°, con-