298 PROCEEDINGS OF SECTION OC. 
phenocrysts, the rock is essentially composed of orthoclase 
felspar laths, and whisps of a peculiar brownish-yellow mica, 
slightly pleochroic, optically negative, apparently umiaxial ; 
its cross in convergent light does not open out appreciably. 
This mica takes readily the form of rosettes, which, in one 
place, have collected into a rectangular aggregate, the out- 
line of which reminds one of the form of amphibole. Besides 
these, iron ores are present in very small quantity (titani- 
ferous magnetite and some pyrite), and in one place, so far, 
a colourless mineral in short laths, which, judging from its 
refraction and double refraction, might possibly be mosan- 
drite; but I have no certain proof of this. At all events, 
it belongs to the numerous elaeolite-syenite minerals of the 
titano, or zircon, silicates. There-is, further, present sporadi- 
eally, in separate grains, a strongly-refractive, rusty-brown, 
transparent mineral, which I cannot identify. Between the 
laths of felspar there is a colourless mineral, the refraction 
of which is only a little stronger than that of the felspar, 
and its double refraction is weak. On staining, it is shown 
to be not nepheline, but albite. Under the glass, I see, 
in two casts of the garnet left behind on falling out of the 
rock, that there is a fine violet coating, which may be fluor- 
spar, and that often the garnet was immediately surrounded 
by pyrite, in which the former left its imprint.” 
A dark-green plagioclase-hornblende rock is found at 
the Regatta Ground. With other associations it would be 
classed as diorite, but seeing that diorite has never been 
recorded in association with the elaeolite rocks, further 
examination is requisite. If it should turn out to be diorite, 
the occurrence will be a remarkable one. 
’ A green rock of dense structure and laminated habit 1s 
found strewn in pieces over the ground just above the Mary 
Mine on Mt. Mary. This is referred to tinguaite-porphyry. 
The ground-mass consists of small felspar prisms, nepheline, 
needles of aegirine, and shows distinct fluidal structure. 
The phenocrysts are sanidine, nepheline, aegirine-augite. 
Instances of fluidal aegirine are now recorded more fre- 
quently than formerly. An accessory mineral in the above 
rock is melanite. 
Certain trachytoid rocks on Mt. Mary occupy an unsettled 
position. Some of them may be effusive, others intrusive. 
Both on Mt. Mary and Mt. Livingstone a singular hauyne 
phonolite occurs, with large porphyritic tabular felspars, and 
pseudomorphs after hauyne. The black iron oxide spots 
scattered through the rock are pseudomorphs after garnet. 
A. light-grey rock on Mt. Livingstone, sometimes with a 
faint bluish tinge, also contains porphyritic hauyne. 
