AUSTRALASIA, NEW GUINEA, AND NEW ZEALAND 771 



nificant in the extreme. It would be instructive also to tell how, 

 in New England, the copper and the gold which were introduced 

 during the Carboniferous folding of Benson occur in the same 

 deposits as a rule, as also do those of the closing Paleozoic both in 

 New England and in the more coastal portions of Eastern Queensland 

 (examples, Drake and Mount Morgan) ; how also in the Carbon- 

 iferous of New England the copper and gold depend upon the ser- 

 pentine belt for their existence, whereas in the Permo-Carboniferous 

 they are related to lamprophyric dykes and basic granitic types. 



In New Guinea the copper deposits appear to be in very ancient 

 rocks, whereas in New Zealand copper is practically absent. 



The tin group of minerals. — Turning, however, from these inter- 

 esting points to the tin-wolfram-molybdenite-bismuth group of 

 minerals in Australia, it may be noted that all four may occur 

 together in certain ore deposits in this continent, but as a rule the 

 deposits of commercial importance may be classed under two main 

 heads. Thus tin is frequently associated with wolfram, whereas 

 molybdenite is associated with bismuth. Should molybdenite and 

 bismuth be associated with other minerals of the group, the prefer- 

 ence is for wolfram rather than for tin. Indeed, the minerals asso- 

 ciated with tin and wolfram, such as tourmaline, topaz, beryl, and 

 quartz with rutile, are practically unknown to the writer in con- 

 nection with molybdenite deposits. 



All these minerals in Australia — tin, wolfram, molybdenite, 

 and bismuth — are associated with siliceous granites or their equiv- 

 alents. In New South Wales the typical tin- wolfram granites range 

 from 75 to 79 per cent silica, while the typical molybdenite- 

 bismuth types range from 72 to 74 per cent silica. These various 

 granites may be distinguished easily by their peculiar vegetation, 

 and appear to have been the hosts of the tin-molybdenite minerals 

 in Australasia. The vapors which conveyed the minerals of the 

 tin group to the marginal portions of the granites, preferably the 

 roofs, or upper and lateral portions, appear to have varied in their 

 power of penetration. Thus the tin and wolfram deposits, with 

 their boric and fluoric associates, are found in many places at slight 

 distances from the siliceous granites themselves, in rocks such as 

 slate, basic igneous rock, or quartz-porphyry. Always, however, 



