725 
Magnetite completes the list of constituent minerals that can he identified. 
The felspars are filled with a granular deposit, some grains of which polarize in high 
colours, and may be epidote. Some rounded grains also are to be observed in the 
felspars, which polarize in high colours and might be put down either as olivine or 
augite, more probably the latter. 
No. 71. Tub Leap, Mackat (Queeijsland). 
A. Gribb Maitland’s Collection. 
Section . — This is another rock whose mineral contents are wholly changed and 
altered. The ground-mass has been micro-granulitic and holocrystalline, with idio- 
morphic crystals of lath-shaped felspars. There are a few fairly large porphyritic 
orthoclase crystals, some of which are '06 inch long, twinned on the Carlsbad type, and 
a few triclinic felspars. The plagioclase felspars show marked fluxion- structure in the 
rock. 
Quartz very sparse, in grains witli rounded edges, carrying inclusions, some of 
which have fixed bubbles, and others are glassy. No moving bubbles. 
A little pyrites and magnetite make up the rest of the rock. 
No. 21. Mount Kinchant, Mackat (Queensland). 
A. Gribb Maitland’s Collection. Sp. Glr. 2'816. 
Colour, grey, speckled with white felspars. 
Section . — One turns with relief from examining the ill-defined wrecks of 
crystals in the last three rocks to this, with its fresh, clean-cut, many-striped felspars. 
Epidote is in fan-shaped groups. Magnetite, much of it sharp ; and apatite in fine 
needles. 
The texture is not holocrystalline, there being a pasty mass of felsitic matter 
separating what would otherwise be contiguous crystals. Fclsp.ars striated many times, 
often over five, and once over forty times. The angle between the axes of extinction 
for each set of lamelloe in the largest felspar is 27° 20) and it measures '161 inch by 
•01 inch. Many of the tabular felspars are built up zonally. 
The epidote is sometimes in rods, decidedly pleochroic ; at other times it is in 
fan-shaped groups, merely showing differences of absorption on rotating the stage 
over the polarizer. 
The magnetite is sometimes in sharp, clean octahedra, and sometimes rounded. 
The apatite, which is sparse, is in fine needles. 
DIORITES. 
No. 246. SWEDENBOEG EeEF, ClIAETEES ToWEES (QUEENSLAND). 
The Hon. H. Mosman’s Collection. Sp. Glr. 2 866. 
Colour, greenish-black. Speckled. Perfectly clear, fresh. Microgranular, 
holocrystalline. 
Section . — The felspars, although minute, are very perfect, often twinned several 
times. Angles of extinction between parallel lamell® vary from 11° to 60°. The 
perfect rulings of these felspars are very beautiful when viewed between crossed 
nicols. Hornblende in about equal proportion to the felspars, showing marked 
absorption and perfect inter.secting cleavages when cut parallel to basal pinakoid, often 
punctured by apatite prisms. Magnetite and possible ilinenite common. One or two 
specks of titanite, being bright yellow with a high index of refraction. Perfectly 
colourless transparent microliths commonly occur in the felspars. Very little accessory 
quartz. 
