117 



Measured Calculated 

 (027) : (001) = 43° 33' 43° 6' 

 (HI) : (OOl) = 81° 28' 81° 19' 

 (ГП) : (010) = 60° 27' 60° 23' 

 (ГП) : (TTl) = 60° 15' 59° 14' 



The tainiolite crystals form elongated bands or strips, 

 attached by one end. The longitudinal direction of these 

 crystals is parallel to the crystallographic a -axis. In the 

 longitudinal zone they are generally bounded only by the faces 

 of the third and the second pinacoids. They are flattened par- 

 allel to the former form, and owing to the thinness of the in- 

 dividuals it is in most cases impossible to determine the faces 

 of the second pinacoid. Only as rare exceptions one meets 

 with crystals thick enough to allow of the determination of these 

 faces. However, individuals have been found with a thickness 

 even equal to their breadth. Such individuals show not only 

 the second pinacoid distinctly developed, but also the forms e 

 and ^ (the prisms of the first order). 



The unattached end of the crystal bands generally is in- 

 distinctly or irregularly bounded. The thin individuals are either 

 split up at the end into a number of points or irregularly 

 ♦rounded. Also the thicker individuals show in general an in- 

 determinable rounding of their unattached end. Only on a few 

 crystals a couple of terminal faces could be determined as 

 belonging to the form p.. 



Fig. 9, Plate III represents a combination of the deter- 

 minable forms (with the exception of b) as occur on crystals 

 of tolerable thickness. On the thin crystals the faces of the 

 third pinacoid are always smooth and brilliant. On the thicker 

 individuals these faces generally are striated longitudinally, which 

 striation is due to an alternation of the principal face с and the 

 contiguous forms Ь or e. The faces of all the other forms are 

 strongly striated parallel to the direction of micaceous cleavage 

 in the mineral. 



