62 



Average лт„..:„»:„„„ Number of Calculated 



, ^- Variations . , 



value measurements value 



£: c = (431):(001) =71°24' 70°58'— 72°13' 4 7i°28' 



г:Ъ = (431) : (010) = 64° 35' 64^18'— 64^57' 



4 64° 36' 



The faces of this form are always of a rather characteristic 

 nature, as well in this type as in the following ones. They 

 almost always look as if they were corroded by some solvent, 

 and are provided with more or less irregular grooves and pro- 

 jections. Most frequently the face is provided with a strongly 

 projecting edge towards the prismatic faces, sometimes also 

 towards the opposite face of the same form. Projecting ridges 

 may also be found crossing the middle of the face parallel either 

 to the edge towards s{l20) or to that towards /г(210). Only in 

 a few cases regular, obliquely placed etching figures are found. 



The faces of this type are other- 

 wise rather well developed , slightly 

 striated. The size of the crystals varies 

 between 1 and 2="°. 



Type IX. 



Vo this belong only a few, very 

 small crystals (1 — 2°"°), all from the 

 same piece; they are not found in con- 

 nection with calcite , but nevertheless 

 they seem to belong hither, as they 

 show some resemblance to the two 

 following types. 



Combination: è{OIO}, s{l20}, 

 i¥{ll0}, A {210}, c{00l}, n[on], 

 e{02l}, /"{041}, P{l0l}, г^{301}, 

 o{lll}, г{121}, £{43l}. Further were 

 found ic{21l) which has before been 

 found in the ilvaite, as well as the new 

 C{33l}, д\б?>\], and r{40l}; the last four forms are only 



Ilvaite, t\pe IX. 



