ON THE KLAPROTHINE OR LAZULITE OF NORTH CAROLINA. 365 
upon these Lazulite crystals as Trimetric combinations, hemihedrally 
modified. From my examination of the North Carolina specimens, 
I cannot but think that this view will in the end prevail. It is 
supported by the fact that in many combinations the upper and 
lower forms do actually correspond in number and character; and 
that practised crystallographers like Phillips and Lévy, skilled in the 
use of the goniometer, were unable to detect in their measurements 
the differences announced by Priifer.* 
The North Carolina crystals—presuming those in my possession to 
represent the generality of crystals obtained at this locality—although 
usually distorted, are of an extreme simplicity: contrasting remark- 
ably in this respect with the majority of European examples. At 
first sight, they resemble a monoclinic prism terminated by a single 
“augite-pair’’ or hemi-pyramid; but they really consist (if monoclinic) 
of two hemi-pyramids, the four planes of one of which are greatly 
elongated ; or, if trimetric (as I conceive them to be), they form a 
rhombic octahedron in which four planes, in opposite sets of two, are 
thus lengthened beyond the others. Fig. 1 represents this distorted 
aspect; Fig. 2, the same form (or combination, if 
monoclinic) in symmetrical proportions. These sym- f 
metrical crystals are of smaller size, and less numerous, 
than the distorted forms. 
Although the edges of these crystals are sharply 
defined, the planes are unfortunately without lustre. 
The most careful measurements of five crystals, by 
means of a fixed or Adelmann’s goniometer gave me 
the same angles for both the upper and lower faces. 
The difference found by Priifer is too slight, how- 2 
ever, to be satisfactorily detected by any kind of 
application goniometer. I attached, therefore, thin 
films of mica as carefully as possible to the planes : 
of one of the crystals, and measured the angles by 
reflected light with a Wollaston goniometer of the 
best construction. The following table shews the measurements thus 
obtained, supporting the apparently Trimetric character of these 
crystals : 
* These observers appear to be the only crystallographers who have practically examined 
crystals of Lazulite. Thus, the measurements of Phillips are followed by Hausmann, 
Breithaupt, and others ; those of Lévy, by Dufrénoy; and those of Priifer, by Naumann 
Dana, Quenstedt, and Miller. 
