TIN-MINING IN NORTH QUEENSLAND. 
377 
When the ore occurs in the lodes with the chlorite the stone is usually 
very good. The country rock adjacent to the lodes usually shows some 
evidence of change, its felspar element giving place to dark-coloured 
hornblendic mineral. Joints in the veins and from the contiguous 
rock generally favour the deposition of tin. 
The ore occurs as cassiterite, and mostly in lenticular deposits, 
varying in size from small pipes up to bodies the whole breadth of the 
lode, and reaching in length to 40 and 50 feet and in depth from a 
few down to several hundred feet. Their yield ranges from 5 per cent, 
to 40 per cent, and over of oxide. Patches of iron pyrites appearing 
in the lodes are considered a good indication. Wolfram, fluor-spar, 
galena, and molybdenite also occasionally accompany the tin. 
Apart from such concentrated bodies, the mass of the mineral 
constituting these chloritic lodes is, for the most part, poor in tin, 
probably not yielding over 1 per cent, of that ore. 
The Great Northern Mine at Herberton has been opened in two 
lodes of the kind just described, and has produced over 4,000 tons of 
dressed ore. In one of these lodes the ore-shoot lasted down to a 
depth of 570 feet, leaving ore in thin seams still in the bottom. The 
shoot was found most productive between 100 feet and 300 feet from 
grass. 
Numerous deposits of ore have been found in veins in the hills 
around Herberton ; but, except those in which chlorite appears as an 
element, they have usually not been very productive. 
Proceeding westward from Herberton toward Watsonville, over 
porphyry ridges, at a distance of about five miles the Main Dividing 
Range is crossed at an elevation of 3,650 feet above sea-level. On 
the western slope of this range the traveller passes over an outcrop of 
stratified rock consisting of greywacke and shales. The North Aus- 
tralian Mine is opened in this formation. In some of the shallow 
working? of this mine the tin is associated with rich carbonates of 
copper, and with iron and arsenical pyrites. The deposits are irregular, 
and occur between bedding planes of the enclosing rock. There are 
faults in the locality, indicating a course by which the tin probably 
arrived at the surface. The North Australian shaft is 200 feet deep. 
At the bottom a level has been driven through mineralised ground, 
toward the north ; but the deep country has not yet developed any 
important tin deposit. At the commencement of this mine the pros- 
pectors discovered a deposit of mineral close to the surface which 
yielded over 400 tons of marketable ore. 
The principal other AVatson ville mines are located on the summit 
and on the northern flank of a portion of the Maiu Dividing Range 
known as the Western Hill, extending two miles onward as far as the 
township of Watsouville. The crown and to a large extent the 
northern slope of the Western Hill consist of porphyry, and the 
tin-bearing veins present much the same features as those at Herberton, 
but the ore is more impregnated with copper and arsenical pyrites. 
The ground is intersected by similar dykes of elvanite. Outcrops of 
some of the lodes yield small quantities of silver. The deepest mine 
is the T Claim, in which the ore-shoot has reached a depth of 330 feet 
from the surface. Several rich deposits of ore have been worked on 
the Western Hill Range, extending to a depth of 200 feet ; but as yet 
