52 
MUSEUM BULLETIN NO. 27. 
In some sections the rock displays a fine, even-grained, granitic 
texture, being composed entirely of fairly stout interlocking prisms of 
vesuvianite. Small druses are seen here and there. The prisms fre- 
quently interpenetrate one another completely, and when this feature 
is pronounced, owing to the intersection of several prisms at a single 
point, it forms a transition from the granitic texture to that now to be 
described. 
In this second type, a radial grouping of the vesuvianite individuals is 
characteristic. The radially orientated prisms dovetail into one another 
at their common point of intersection and give rise tospheres,or, in section, 
to circular aggregates. The spaces between these radial groups may be 
filled with vesuvianite showing the ordinary massive intergrowth, or 
may be left vacant as druses; many of them, however, contain rather 
coarsely crystallized colourless diopside, as well as some smaller grains 
of colourless garnet, both of which are contemporaneous with, or slightly 
later than, the vesuvianite. Plate X is reproduced from microphoto- 
graphs of this rock, and clearly illustrates the various features referred to. 
Druses within this rock are lined with beautiful lustrous crystals 
of vesuvianite, paler in tint than the rock mass, and rather like kunzite 
in colour; with a further decrease in the depth of tint, the crystals are 
sensibly colourless. 
The crystals are fairly rich in forms, those usually present being 
c(001), a (010), m(110), f(120), p(ill), s(131), z(12l), i(133), and t(331) 
(see table on page 58); h(130) and d occur less frequently and for the 
most part their development is relatively smaller. The average habit of 
these crystals is shown in Figures 17 and 18. The basal plane is always 
present, but small, and, especially in the more deeply coloured crystals, 
it has a drusy surface. The prisms a(010) and m(110) are both promi- 
nent and vary in relative size, sometimes the former and sometimes the 
latter being the larger form. Of the pyramids which terminate the 
crystals, the unit pyramid, p(lll), is invariably the most prominent, 
with the ditetragonal pyramid, s(131), rather smaller. Faces of the 
latter form are usually heavily striated in the zone [a s], as shown in 
Figure 19, and the same striae appear on the prism faces. When such 
crystals are examined on the goniometer, this feature gives rise to a 
continuous string of images connecting the bright signals from a(010) 
and s(131) and readings taken at the brighter points in such chains of 
light on a large number of crystals show a tendency to the develop- 
ment of the forms v(151), (272), and y(141). The first of these occurs 
as a true form on some of the pale yellow crystals described below, but 
(272) and (141) were not observed as well established forms on any of the 
crystals measured from this area; the form (272) would be new for 
vesuvianite. In many of these crystals, the faces of the prism a(010) 
