64 CATALOGUE OF MINERALS ; 
general parallelism, sufficiently disproves this theory. Crystallization is 
comparatively rare, and the lamination seems to imply by no means 
segregation of the silica from the surrounding strata, but rather deposition 
of silica during the passage of copious sheets of hot water charged with 
the mineral in solution. The veins . . . can be followed from hill-top 
to hill-top, forming at times rough insurmountable walls a hundred feet 
high—as, for example, in the peaks west of Mount Tenison-Woods. In 
other places denudation has left their remains on hill sides or hill tops in 
the form of hugh cubes of hard quartzites, from which the surrounding 
softer rocks have crumbled away. The cubes stand up weird and solitary, 
like the ‘perched blocks’ of alpine and arctic lands. 
4 Similar veins, it may be here observed, have been noted by 
me in the Cloncurry and Leichhardt region, where they attain still more 
gigantic proportions. The veins of the Cloncurry and Hodgkinson 
resemble the dolerite dykes of Scotland and Ireland more than the ore- 
charged reefs of Australia. The Hodgkinson veins, I have been informed, 
contain rare and minute quantities of gold. I have not been able to verify 
this information, and I suspect that the gold may have come from reefs 
adjacent to the veins. Specular iron ore, brown hematite, and binoxide of 
manganese, are not uncommonly found in cavities in the larger veins, but 
I have never seen either in payable quantities.” 
Onyx and hornstone occur at Springsure, and amethysts have 
been found on the Logan River and at Mackay. 
Flint is mentioned by Mr. Jack as occurring in Police Creek, 
Gregory Downs, and chert has been met with at Mackay, and 
Springsure, and Ravenswood. 
Smoky quartz (Cairgorm) occurs in large crystals at Stanthorpe, 
and also on the Main Range below Toowoomba. 
Clear quartz containing fluid cavities has been found at Mackay 
and in ihe Logan Valley and elsewhere, and Mr. R. L. Jack, 
writing about a dyke which runs S.E. through the “country” of 
the Queen line of reef, Charters ‘Towers, says, ‘‘Sections of the 
rock forming the dyke in question, on being examined under the 
microscope, show a matrix of felspar a good deal coloured with 
chlorite, with blebs of clear quartz containing numerous fluid 
cavities.” 
Silicified wood is of not uncommon occurrence, especially in 
basaltic country ; many specimens have been obtained from the 
Darling Downs and other localities. A specimen in the Queens- 
land Museum Is worthy of special notice for it contains imbedded 
it in a nail or other bit of iron; this came from a steep bank at 
Chinchilla, near the Head Station, and as this district has only 
been opened up in recent years (about 1842), the specimen 
shews how rapid the silicification of the wood has been, as the 
nail must have been driven into its place before the wood 
became altered, 
