Geology and Mineralogy. 235 
acters, the author goes on to mention some highly altered clpen 
observed near the ‘Village of Tavacly. In this altered granite the 
polarization; the mica and hornblende have completely disap- 
peared and in their place there is a greenish fibrous substance 
found in the fresh rock; the zircon is unchanged, but the titanite 
has also completely disappeared. It is to the last change that the 
greatest interest is attached. The mineral which has taken the 
ormer isotropic, the latter ve naxgnar detinie: rea with the 
acadaba case parallel to the diagonals. shan 
system is thus found to be scaregciint: the form tha t x ‘a squa 
pyram iid Cleavage eg to the base and to the pyramid cm 
also observed. By use of the Sanstadt solution the specific grav- 
ity was found to be caneees 3°6 and 4°5. so under the micro- 
scope the terminal bynes angle was determined from the sec- 
tions to be 98° 24', and the basal edge of the rhombic sections 
136° 16’. These angles, as also the characters previously given, 
i , the presence o 
