The Gold Deposits of Mount Morgan, Queensland. 331 



cled by a small stream (Mundic Creek) and is in many 



respects distinct in position and geological structure from 

 the hillocks about it. The crest of the hill is being 

 rapidly broken away in the quarrying operations, from 

 1200 to 1700 tons per week being removed. 



In a report published in 1884, Mr. Robert L. Jack, the 

 Government Geologist of Queensland, described this 

 remarkable deposit and put forward an explanation of its 

 origin. This report has, after a lapse of some ten years, 

 been reprinted with a few notes and corrections, and the 

 following extract from it presents Mr. Jack's views as to 

 the mode of occurrence and genesis of the deposit : — " In 

 the immediate neighbourhood of Mount Morgan the 

 country rock consists mainly of bluish-grey quartzite — 

 a fine-grained siliceous sandstone, now more or less 

 vitrified — full of minute crystals of iron pyrites and 

 specks of magnetic iron-ore, greywackes of the ordinary 

 type ; hard, fine-grained sandstones or mingled siliceous 

 and feldspathic materials, now somewhat indurated ; and 

 lastly, occasional masses of shale hardened to a flinty 

 consistency, — and a few belts of serpentine. The strata are 

 of cretaceous age, and the sandstones above mentioned are 

 sometimes charged with auriferous pyrites to a remark- 

 able extent, and although large tracts of these pyritiferous 

 tjuartzites are too poor to be worked, recent explorations 

 have disclosed a large body assaying from half an ounce up 

 to 174 ounces of gold to the ton. "'"As the stratified rocks 

 in this locality appear to have been in thick beds, and as 

 their metamorphism has gone to a considerable length, it 

 is not easy to be certain of either dip or strike. The 

 stratified rocks are, moreover, interrupted and intersected 

 in every direction by dykes and other intrusive masses of 

 dolerite (itself altered by the substitution of viridite for 

 augite or olivine), trachyte and other igneous rocks, the 

 intrusive masses apparently occupying as much space as 

 the remnant of the original stratified formation itself. 



