10 PROCEEDINGS OF THE NATIONAL MUSEUM. VOL. 62. 
by crowding, their terminations diverge sufficiently to permit idio- 
morphic development. Several trials, however, showed that these 
are totally unsuited for goniometric measurement, the prismatic 
planes being exceedingly wavy, while the broad faces of the dome 
»(101) and the narrow faces of the basal pinacoid c(001), while 
transparent, are etched to complete dullness and give only the faintest 
reflection and no signal whatever. Only qualitative measurements 
were obtained, and these indicate the forms present to be (010), 
m{110), (101), and ¢(001). The aspect is chisel-shaped, as shown 
in the drawing, Figure 10. 
