728 
and the whole space occupied by the late crystal is now filled by little specks of a 
highly-coloured mineral (between crossed nicols) in addition to dusty kaolin. The 
specks may be mica or epidote. 
ISTo. 95. Atherton’s Creek, Mackat (QuEENsnANn). 
A. Gibb Maitland’s Collection. Sp. Gr. 2'66. 
Colour grey, with small black specks and small flesh-coloured felspars. 
Section. — h’elspathic spherulitcs, contiguous, without interstitial paste, but some- 
times with intervening microgranulitic quartz. Dusty porphyritic felspars, packed with 
specks showing high colours between crossed nicols. These specks are distributed in a 
base whose definition is hazy and sufEers partial extinction on rotation of the stage, 
while some of the specks remain illuminated in all azimuths. The felspars measure 
from ’01 inch to ’02 inch, and some show faint twinning bands. Occasional porphyritic 
quartz, very much corroded. Some ill-defined chlorite and very sparse apatite. 
No. 5. GtMPIE (QuEENSLANn). 
11. L. .Tack’s Collection, “ Greenstone.” Sp. Gr. 2’49. 
Colour green, with white streak, and speckled with slightly deeper green spots. 
Section . — It is not easy to describe this rock. It is highly metamorphosed, 
no component mineral being now in its pristine state, with the exception of a few small 
augities, whose sections are parallel with the basal pinakoid, and .show cleavage parallel 
to prism-faces (parallel to 110). They are the only shining lights of the section, except 
doubtful epidote grains. There is a pasty ground-mass filled with felspar microliths. 
The porphyritic felspars are impossible to name : they merely present confused 
kaolinized patches with opaque specks, which, by reflected light, are found to be milk- 
white. 
The hornblende or augite cavities, on the other hand, show light, bright-green, 
V'ery translucent patches, polarizing in very low colours, almost requiring the quartz 
plate to discern, in many cases associated with a little apatite. This light-green mineral 
of secondary origin might be chlorite, oi*, as Mr. Jack suggested, viridite. In one or 
two cases there is a lattice structure, polarizing in vague blue slate colours, but it is 
ill-defined. 
At first sight the section looks xincommonly like a porphyry. The lattice 
structure may possibly be serpentinous, and derived from the pre-existent augite. 
New South W ales. Marked “ Intrusive Dyke-stone from the Peak.” Plate 60. 
The late Mr. C. S. Wilkinson’s Collection. 
Colour, dirty brownish-red, coloured with green spots. 
Section . — The chief interest of this rock lies in the abnormal development of 
epidote, which, in fan-shaped groups and green laths, fills the space probably at first 
occupied by augite. The colours between crossed nicols are very high. The index of 
refraction is high, and the pleochroism is fairly marked, so that there is little doubt 
about the presence of epidote ; but there is an uncertainty with regard to the percentage 
of these cpidotes, lor in no single instance has the change been incomplete. The shape 
and angle of the prisms suggest augite. Originally the crystals were perfect m shape, 
since the outlines are even now clear and sharp. The prism-angles I made out to be 
about 88°. There is abundant apatite, and there are also transparent red grains, 
while ferritic matter is developed with and alongside of the epidote. The rest of the 
section calls for little description, the ground-mass being microfelsitic. The porphyritic 
