310 JOURNAL OF SCIENCE. 
common mica. Crystalline outlines were not observable on any 
of the specimens. On trying to determine the optical character 
of the scales by the polariscope, their insufficient transparency, 
if of sufficient thickness for the purpose, did not allow the 
observing of a well-defined interference figure, but so much could 
clearly be seen that this mica is biaxial with a rather large 
angle (2 E.)-about 70°-80°-between the optic axes. Before the 
blowpipe the mineral (fine green scales) imparts to the borax 
bead, both in the oxid. and reduc. flames a fine emerald-green 
colour, indicating the presence of a not inconsiderable per centage 
of chromium. 
Chromite (Chromic [ron)—This ore occurs also in the layer 
containing the chrome-minerals just described, and is sometimes 
associated with the fuchsite. What renders it worthy of special 
reference here is that, different from its generally massive mode 
of occurrence in the Nelson district and other parts of the island, 
it isin this case more or less abundantly impregnated in a feld- 
spathic base in lustrous black crystals, representing perfect octa- 
hedra, varying from finest black specks to over I mm. in size. 
It is very likely that on washing the surface detritus, near the 
ore-layer, good samples of sand of this crystallized chromite might 
be obtained, as is the case in the Heathcote district, Victoria, 
and at the Arthur River, Tasmania, where the mineral is derived 
from decomposed serpentinous rocks. 
Rutile-—Mr. Docherty brought this mineral from his previous 
prospecting trip, and it is one not hitherto noticed as found in 
New Zealand. It occurs associated with titaniferous iron in a 
feldspathic matrix in one of the N. and S. layers. The crystals 
are up to 12 mm. in length, and from 1 to 5 mm. in diameter, 
and present the common prismatic type deeply striated vertically, 
with the terminal planes too badly developed for determination. 
A crystal disclosed on breaking one of the feldspar pieces proved 
to be a metagenic twin (see fig. 3). The lustre of the crystals is 
rather poor, indicating that they are somewhat affected by de- 
composition; their colour is blackish-brown, on fracture 
splinters are sub-transparent brownish-red. 
Prochlorite—The dark green massive chlorite rock of the 
supposed branch of the large dyke at the seaboard, near the 
western boundary of the schist-area is, as far as the specimens 
brought by Mr. Docherty show, entirely devoid of any schistose 
structure ; but it contains in abundance irregular cavities, some- 
times narrow, fissure-like, in which the mineral constituting 
the rock has crystallized out in vermiform curved hex- 
agonal prisms, also, though more rarely, in divergent, 
fan-shaped groups of scales. Its hardness was _ found 
less than 2, spec. gravity 2.968 (mean of a number of determina- 
tions). Though their characteristics seemed to refer the mineral 
to Dana’s species prochlorite, still on considering that ripidolite 
is perhaps more commonly found to form rocks of this class, as 
well as chlorite schist, and as examination before the blowpipe 
affords no distinguishing reactions between tne two species, it 
