279 



district, where considerable gold occur*, lioth in 

 alluvial gravels Hn ,| j n wdl-fbrmed quart/ veins 

 traversing tin* Lower Silurian Lingula IMM|* anil 

 tin' intruded iliuluisic rocks calle<l ' greenstone ' in 

 the Geological Survey. A peculiarity of the. veins 

 is t IK- miniMon association of magnesian minerals. 

 The gold i.s about 20 or 21 carat line, ami often 

 .shows trao-- >i' iron ses(|uioxi(le. So long ago as 

 Isiil some t'HUMMi worth of gold per annum was 

 taken out of the Clogan mine by imperfect 

 methods. Some samples have atl'onled 40 to 60 

 ounces per ton -a most remarkable yield. There 

 are probably many veins still awaiting discovery. 



To quote another European example, Hungary 

 afforded the Koman conqueror fabulous riches, 

 and will yet produce untold wealth, when 

 the capitalist shall condescend to look so near 

 home. Statistics concerning the annual gold 

 output of the world are for many reasons only 

 approximately correct. In countries where a 

 royalty is payable on the gold mined 'returns' 

 are sure to be much below the actual yield ; while 

 in uncivilised lands no record is kept. Therefore it 

 is not easy to arrive at a computation of the yearly 

 production. But it is certain that the tendency 

 in 1881-90 was toward a decline rather than the 

 contrary. This is due to the fact that the enormous 

 placer deposits of many regions had to a great 

 degree been worked out ; anil, though vein-mining 

 was extended as the placers failed, the extraction 

 of gold from the vein-stuff was a slower and more 

 costly operation, requiring a larger expenditure 

 of capital and employing more labour. Thus, 

 the great yields obtained between 1850 and 1870, 

 reaching 30 to 40 million pounds sterling annually, 

 were the result of extensive placer operations that 

 gradually ceased. In 1881-90 the average pro- 

 duction was 21,738,000. But the development of 

 gold-mining was such that in 1896 the production 

 was more than double, approximately 4f>,000,000, 

 distributed thus : United States, 10,'800,000 : Aus- 

 tralasia, 8,988,000 ; Trr.nsvaal, 8,604,000 ; India, 

 5,911,000; Russia and other countries (including 

 British Guiana, British Columbia, &c.), 10,697,000. 

 This did not include any gold from the enormously 

 rich field of the Klondike, &c. , in the upper Yukon 

 valley, which began to attract notice only in that 

 year. Other recent developments were those in 

 the Transvaal (q.v.) and Western Australia (q.v.). 

 From 1850 till 1896 the total gold production was 

 estimated at 300,000,000 ounces, with a value of 

 1,163,000,000. For the appreciation of gold and 

 the economic questions thence arising, see BI- 

 METALLISM. See also GILDING, GOLD-BEATING. 



Geologically, as well as geographically, gold is 

 widely dispersed. The early geologists propounded 

 theories concerning the age of geld deposits which 

 did as much to retard the development of gold- 

 mining as to promote it ; for while they indicated 

 certain formations as Ireing probably auriferous, 

 and drew attention to them, they, on very slight 

 grounds, pronounced other formations to be posi- 

 tively non-auriferous, and thus dissuaded prospec- 

 tors from studying beds which almost accidentally 

 have l>een .found to l>e rich in gold over enormous 

 areas and to great depths. In the light of modern 

 explorations it would be unsafe to say that any 

 formation must a priori be barren of gold. On the 

 contrary, its presence may be always anticipated, if 

 not in workably paying quantity, until its absence 

 has been proved. 



The origin of gold-bearing mineral veins is 

 inseparably connected with that vexed question, 

 the origin of mineral veins generally (see ORE- 

 DEPOSITS). Suffice it to say here in brief that, 

 while one class of geologists ascribe it exclu- 

 sively to igneous agencies, another class as stoutly 

 defend a theory of aqueous solution. It is not 



unreasonable to nupixwe that the truth lien between 

 tin- two parties that some depotutA are due to 

 jiliitniiio and others to aqueous origin. Gold ha* 

 pen found and worked in nicks of undoubted 

 igneous origin and of primary age. It ban alno 

 Keen found in the interstices of a lava ejected 

 within historic times. On the other hand, ito 

 presence has l>een proved in the water of the seas 

 surrounding the British Islands, and in the deposit 

 formed by hot springs now in activity. Speaking 

 broadly, a gold deposit may I"- of any geological 

 ag^e, from that of the oldest rocks to that of rock* 

 still in course of formation. But hitherto it* 

 presence in notable quantity has been chiefly 

 proved in connection with certain formations. 

 Taking the sedimentary rocks in chronological 

 order, the chief auriferous regions may le classified 

 as follows : Metamorphic rocks afford the chief 

 gold-supplies of Nevada, South Dakota, Siberia, 

 Hayti, India, Japan, and New Caledonia. Lauren- 

 tian rocks are auriferous in West Africa, Brazil, 

 and Canada ; Cambrian in Nova Scotia and Brazil. 

 Silurian is the great gold formation of Australia, 

 and figures in New Zealand, French Guiana, and 

 the Andes. Devonian age is ascrilied to some of 

 the gold of Cornwall, Siberia, and Australia. The 

 coal-measures of Queensland, partly of Carbon- 

 iferous and partly of Permian age, enclose the 

 Gympie gold field ; and some of the gold l>eds of 

 New Zealand, New Brunswick, Nova Scotia, New 

 Mexico, Ladakh, India, New South Wales, and 

 Somersetshire are of Carboniferous age. The 

 Jurassic formation has not proved of lunch im- 

 portance, but affords some gold in Europe and 

 Mexico. Triassic rocks are abundantly gold- 

 yielding in California and Mexico. Chalk is prob- 

 ably as little associated with gold in men's 

 minds as is coal, yet the Cretaceous rocks of Cali- 

 fornia, South Dakota, New Zealand, Queensland, 

 Afghanistan, and Hungary afford large supplies of 

 the precious metal. The Tertiary gravels of the 

 western states of America and of Australasia have 

 been the source of the enormous yields of placer 

 gold from those countries, and embrace thousands 

 of square miles of Miocene, Pliocene, and Post- 

 pliocene beds resulting from the erosion and 

 disintegration of the gold-carrying veins of the 

 older rocks. 



Of the igneous rocks with which gold is associated, 

 diorites hold a foremost place in Hungary, Nevada, 

 New South Wales, Victoria, Queensland, South 

 America, Italy, the Urals, India, Turkestan, New 

 Guinea, and New Zealand. Granite, syenite, and 

 gneiss are auriferous in Colorado, Virginia, Carolina, 

 South America, Canada, Australia, Turkestan, 

 Asia Minor, Hungary, and Siberia. Porphyritic 

 rocks carry some of the gold of Queensland, 

 Victoria, New Zealand, Borneo, and South 

 America. The serpentines of Queensland and 

 Newfoundland have yielded gold ; while the 

 trachytes of New Zealand, South Dakota, Mexico, 

 Queensland, and Hungary are important gold- 

 carriers. 



By far the most common matrix of vein-gold is 

 quartz or silica, but it is not the only one. To pass 

 by the metals and metallic ores with which gold is 

 found ( because it will be more convenient to deal 

 with them when speaking of the treatment 

 necessary to release the gold), there are several 

 other minerals which serve as an envelope for the 

 precious metal. Chief among them i> lime. Some 

 of the best mines of New South Wales are in 

 calcareous veins. Sundry gold reefs in Queensland. 

 New South Wales, Victoria, and Bohemia are full 

 of calcite. Dolomite occurs in Californian and 

 Manitoban mines; and apatite, aragonite, gypsum, 

 selenite, and crystalline limestone have all proved 

 auriferous, while in some cases neighbouring quart* 



