GOLD MINING AND METALLURGY. Gold is found in nearly all parts of the world and small amounts occur in ocean water and in many rocks. It is mostly in such minute proportions, however, that it cannot be profit ably extracted and only the more concentrated deposits can be utilized and some of these only where natural conditions are favorable. It oc curs in all formations from Archean to Quaternary and in part in association with various other metals as silver, copper, tellurium, lead and iron. The pure metal usually occurs in connection with silica or quartz, so that lode and vein gold mining is generally known as quartz mining. Gold has always been precious and difficult to obtain and never has been found so plentiful as to still the desire for its pos session. In its search and exploitation, nature has generally demanded full toll in labor and effort. With early, primitive methods only the easily accessible, pure gold was obtained, but as machinery was developed and processes of ex traction perfected, mining was extended to the less rich deposits. This development has pro gressed in other lines of mining so that within the last 25 years the production of iron, copper, coal and petroleum has been greater than the aggregate of all previous times.
History of Gold The earliest records of gold mining are from Egypt, where pictorial rock carvings indicate the breaking up of ore by stone hammers, its grinding in stone mills, and treatment with water on stone tables. Shallow earthen dishes were used for final washings. Inscriptions on monuments indicate that gold washing was done as early as 4000 The Argonauts' search for the Golden Fleece has been explained by the fact that fleeces have been used effectively to catch fine gold in ditches and flumes, and when much gold dust adheres it makes a veritable golden fleece. The Argonauts are supposed to have made their quest in the direction of the famous gold deposits of Colchis, west of the Caucasus. Herodotus, 484-425 B.c., refers to several great gold mining centres in Asia Minor, and Strabo, 63 B.C., and Pliny, 23-79 A.D., mention gold mining in many different places. Pliny gives many details of ancient placer mining, which was extensive, for the water used was carried great distances by long ditches which crossed valleys in aqueducts. Inplaces ledges were
cut away to make room for troughs of hol lowed-out logs. These and other ancient writers clearly indicate that gold mining was carried on in Egypt, Asia Minor, Italy, Greece, Spain, France and India before the Christian era.
History gives no reliable records of the out puts of these different gold fields, but doubtless they were small as compared with modern re turns. Rome's wealth in gold increased as she took possession of the world, and finally reached a high figure, but during the barbarian in vasions this accumulation of gold was scattered, and gold mining languished in the Middle Ages.
In the 13th century discoveries in the Alps, Transylvania and various parts of Spain re vived production. In the 16th century the discoveries of gold in Mexico, Peru, Colombia and Chile gave new life and system to gold mining and since that time the gold production of the world has been estimated with a fair degree of accuracy. Considering, however, the great part that metals have played in civiliza tion, it is astonishing that we have but meager accounts of the details of their obtainment. Agricola's We re Metallica,) in 1556, gave the first extensive and reliable information, with maps or illustrations, of any class of mining. This work, written in Latin (translated by Mr. and Mrs. H. C. Hoover), is the beginning of accurate mining and metallurgical literature. In this work applianceS and methods used in both alluvial and lode mining are described and illustrated. It shows that the principles of many of the modern devices used in placer and other mining had long been known. A primi tive stamp mill is described, also the use of quicksilver, retorting, assaying, melting and refining of gold and silver. The relative extent of ancient and modern gold mining is shown in the following table, which gives the output from the world's mines, with average annual progressive showings from 1493 to 1917, in clusive: The contributions of the most important countries, with dates of initial operations, are approximately as follows: Gold mining is divided into two classes, placer mining and lode or quartz mining.