TIN-MINING IN NORTH QUEENSLAND. 
379 
In the Tate district the country rock is granite. At Mount 
Borunda, in that locality, the ore is developed in floors of decomposing 
granite, which stretch along the outcrop of the lode. In this case 
muscovite forms a prominent feature in the stanniferous matrix, and 
the ore is very free from foul mineral. None of the mines are much 
troubled with water. Shafts sunk in the sedimentary rocks encounter 
most water, those opened in the porphyry being comparatively dry. 
ALLUVIAL MINING. 
When tin ore was discovered in the detritus from the lodes, the 
search for alluvial ore naturally took an active form, and it has so con- 
tinued ever since. Most of this class of ore is derived from open 
gullies. It is also obtained from drift now covered by rock of volcanic 
origin. Titanic iron at times accompanies the tin, but this takes 
place more particularly in some of the western country, and where 
the tin-bearing drift lies under decomposing basalt. Gem-stones are 
likewise found. 
South of the town of Ilerberton a large area of tin-bearing drift 
occurs under a sheet of basalt, having no doubt been brought there 
from the adjacent hills. It is chiefly worked by tunnelling from the 
Wild River Plats, the tunnels serving for drainage and transit-ways 
from the mines to the surface. Shafts sunk through the basalt to the 
alluvium go to a depth of 60 feet. In some places a sandy drift settles 
down between the stanniferous gravel and the volcanic rock, and in 
others the basalt lies close down on the wash itself. The ground 
mined over extends to a length of 3 miles, the most important por- 
tion of which, at Nigger Creek, seems to have formed the site of a 
small lake resulting from the meeting of streams from the surround- 
ing country. The gravel varies in thickness from a few inches to 3 or 
4 feet. The average yield of the gravel is about 50 lb. of tin ore 
to the ton, or 2i per cent. The grain of the tin is generally well 
rounded, and the colour grey. Grains of gold are found in this 
alluvium, but in no appreciable quantity. 
Alluvial tin is worked in the gullies and creeks of the granite 
country between Ilerberton and Coolgarra, and in the vicinity of that 
township. Veins showing tin crop out in the granite, but no mines of 
any importance have yet been opened in them. The Innot mineralised 
hot springs are situated in Nettle’s Creek, one of the tin-producing 
streams of the district. 
The California Creek granite country, and the Tate River and 
Possilbrook granite and porphyry ranges beyond, are sources of stream 
tin. The Tate district has produced ore of this class during the last 
thirteen years. ♦ 
PRODUCT OF TIN ORE. 
The quantity of marketable tin ore produced in the whole district 
from the discovery of the field in 1878 to the end of 1893, as obtained 
from official documents, is 24,845 tons. Of this 4,704 tons may be 
estimated as stream tin, and 20,141 tons as the result of lode-mining. 
The districts of Ilerberton, W atsonville, and Irvinebank have produced 
nearly equal quantities of lode tin, the preponderance being at the 
