26 AOTTIVEESAET ADDEESS. 



rock. This is the case at Morro Yelho. The sulphides consist of 

 magnetic iron pyrites, which is most abundant, and yields a little 

 gold ; common pyrites, which is less abundant, and gives more 

 gold; and mispickel, or arsenical iron pyrites, which is the 

 principal gold-bearer. 



A similar change from gold to the sulphides (holding gold) was 

 reported to me by the late energetic Grold Commissioner at 

 Eavenswood, in Queensland, INIr. Hacket, and in fact it is a 

 universal law from which there is no exemption, even at Hawkins's 

 HiU. 



Mr. Arthur Phillips also points out the same fact in Brazil. 

 IVIr. Hockin, the director of the Morro Yelho mine, stated to Mr. 

 Phillips that the composition of the pure ore may be taken at 

 about 43 per cent, of silica and 57 per cent, of pyritous matter. 

 Such ore yields by assay from 4 to 6 ozs. of gold per ton ; and 

 where crystals of this mineral make their appearance the yield 

 of the precious metal is large. Cubical pyrites is of more 

 frequent occurrence, but is far less rich in gold. Solid specimens 

 of this substance, but slightly mixed with quartz, yield about an 

 ounce and a half of gold per ton. Magnetic pyrites yields rather 

 less than 4 dwts. per ton. Bunches of clay slate are often found 

 in the principal veins, and this rock, by assay, affords from 5 to 

 7^ dwts. per ton. 



" Quartz without any admixture of sulphides," he says, " has 

 never been found to be auriferous, and it is a remarkable fact 

 that the smallest speck of gold is rarely seen previous to the 

 concentration of any of the ore in the mine." 



Mr. "Weddell says that the old miners at Grongo Soco once took 

 out £100 in three hours — (Hartt, p. 541) — a feat which certainly 

 beats most of our Australian gold-doings ; though, perhaps, it 

 did not take even so long to knock to pieces the famous hundred- 

 weight of 1851. Prom that mine the annual income for three 

 years was £1,388,416, of which £375,163 was profit. I would 

 repeat here, that where certain igneous rocks are present, such 



