76 MARIE BENTIVOGLIO. 



only the minority were of value for goniometric work. The 

 crystals observed all belong to one type, as exhibited by 

 the only single crystal found. Doublets are common, but 

 triplets and fourlings also occur. The crystals are singly 

 terminated, except in the more complex groups, which are 

 doubly terminated and where the point of attachment to 

 the rock matrix is the a face. A stout prismatic habit 

 prevails, and the prisms, with the exception of a (100), are 

 strongly striated; the basal pinacoid is usually present as 

 a pitted face giving indefinite signals, and z (231) occurs 

 as very small faces. The forms developed are a (100), 

 c (001), h (120), r (230), B (570), k (340), A (780), m (110), 

 e (101), s (111), t (133), z (231) and (540); the last mentioned 

 face is not listed in Goldschmidt's "Winkeltabellen." The 

 most commonly occurring forms are a (100), h (120), m (110) 

 and z (231). 



The doublet examined from Pheasant Greek has the 

 following forms developed: a (100), h (120), r (230), m (110), 

 s (111), z (231), N (241), M (8.15.4) and R (13.17.6). JV, M, 

 and R are rare forms occurring also on crystals from 

 Pitk'aranta. 



The crystal from Stanthorpe is large and doubly termin- 

 ated, the primary pyramids being very prominent; in habit 

 it is tabular. Daring development, oscillation has occurred 

 between this crystal and the small twin it supports at one 

 end. 



The doublet described from Mandoie Station consists of 

 a large crystal of bipyramidai habit and a small segment 

 in twin position. The prism zone is reduced to a few small 

 faces a (100), r (230), m (110) and h (120), and the pyramids 

 s, e and z are prominent. 



In conclusion I wish to express my indebtedness to Pro- 

 fessor Sir Edgeworth David for the encouragement given 

 and the interest he has always taken in this investigation. 

 To Assistant-Professor L. A. Cotton my best thanks are 

 due, for his kindness in placing the material at my disposal, 



