I 



EXPLANATION OF PLATE 37. 



BENITOITE. 



1. Very common habit: e(0001), p(10Tl), Tr(OTll), m(10T0), M (0T10). 



2. Common habit with minute or no basal plane. The diminution of 

 the basal plane is practically always accompanied by diminution of the 

 positive pyramid. 



3. A rather common habit, where 2>(10T1) intersects c(0001) producing 

 a hexagonal outline on the base, very rarely approaching an even develop- 

 ment of positive and negative planes and giving a pseudo-hexagonal habit. 



4. This figure without x is a type of a fairly common habit in which 

 the irAir edges are truncated by r(10T2). The form x, of doubtful index, 

 here taken as (To.1.9.10), occurs on but a few crystals and was observed 

 complete only about one terminal of a lateral symmetry axis, though here 

 represented complete for the three axes. 



5. Diagrammatic representation of etch figures. The planes of the 

 upper half of a crystal are supposed rotated about their upper horizontal 

 edges until they all lie in the plane of e(0001). Where differently shaped 

 figures appear on the same form they represent the more common types 

 and variations, or the effects produced by distinct development of internal 

 planes. The broken lines represent the traces of the lateral planes of 

 symmetry. 



