876 
PROCEEDINGS OF SECTION C. 
covering a radius of nearly 40 miles. Alluvial mining has been 
carried on in the same direction from Herberton to the Tate Kiver 
and Eossilbrook, a distance of over 80 miles. Within the same limits 
are developed other minerals of economic value, including lead, silver, 
copper, antimony, and wolfram. The gold-mines of the Hodgkinson, 
Mareeba, and the Eussell lie to the north and east. 
LODE-MINING. 
The following observations apply more especially to the neigh- 
bourhood of Herberton : — 
In this locality the preponderance of the outcropping tin- 
bearing rock is porphyry. Where seen in the deep ground this 
rock assumes a granitoid structure, and hornblende at times is 
present as a constituent. The decomposition of the felspar is 
characteristic, and streaks of carbonate of lime may be observed in 
some of the rock joints. White mica is not much present, there being 
a difference in that respect from the granite country to the west. 
Tourmaline is likewise rare, contrasting thus with the stanniferous 
rock at Cooktown. 
There are outcropping patches of granite, but their extent is 
limited. 
The country is subject to what miners term ts slides,” normal and 
reversed faults, both being encountered in the mines. It is also 
traversed by dykes of elvanite of varying thickness, intersecting the 
lodes at different angles. In two instances, at Herberton and Watson- 
ville, where I have seen such dykes driven through at 300 feet from 
the surface, a clay seam was followed conforming to the strike of the 
lode, and the lode fissure reached on the other side ; but the lode wns 
not shifted, nor was its course changed. In these instances the dykes 
were not in themselves stanniferous, but tin was present in the lodes 
at a short distance from them, 
Mr. B. L. Jack, in his geological report, describes the tin- 
producing veins of this district as metamorphosed igneous dykes, 
having probably a diorite origin, and at present consisting mainly of 
quartzose chlorite and quartzose serpentine. In deep ground I have 
observed that these veins develop more quartz, and present a greater 
resemblance to ordinary lode veins, the enclosed mineral being in a 
more banded form and parallel with the walls of the enclosing fissure. 
Eor convenience of description they will be referred to as lodes in the 
following remarks. 
The strike of these dyke lodes is more or less meridional, but 
they have no uniformity in that respect, varying in all directions ; nor 
have they in the direction of their dip, which is sometimes to the right 
and sometimes to the left, generally at a steep angle. In length they 
have been traced at surface and underground several hundred feet. 
In width they vary from 1 or 2 to 25 feet wide, and suddenly expand 
and contract. 
The deposits of tin do not always take place in the chloritic 
mineral filling up the main fissure, but are sometimes found connected 
therewith as branch veins, and in such cases the matrix of the ore 
consists mainly of quartz, the chlorite element being less prominent. 
