MINING. The art of obtaining from the earth the metallic ores and other useful minerals in an economical and profitable manner. The earliest metals employed by man were those found in the native state. Gold is the most wide ly distributed of these, and has been mined and utilized from very remote times. Meteoric iron was also known and utilized by many ancient peoples, and the native copper of Lake Superior was extensively mined and utilized by the aborig ines of America. As. however, the knowledge of metals increased and civilization advanced, the ores, or metals in combination, were recog nized and utilized and mining proper began. Reference is made to mining, in the Bible, and other ancient records prove that the Placnicians navigated the seas as far as Cornwall, England, in order to obtain tin ores for the manufacture of bronze. The Romans had extensive mines for iron ore in the island of Elba that are still in operation. They also worked the great copper veins at the Rio Tinto, Spain. and the timbering left by them is still visible. The mines at Lauri um, Greece, were famous in ancient times for their yield of silver. From the old mining districts of Cornwall and from the Erzgebirge (Ore Mountains) and the Harz Mountains in Germany miners have gone all over the world, and under their tuition the mining practice of to-day has grown up in all the newer dis tricts.
Problems in Mining to-day may he grouped into those relating to: ( ) mining geology; (2) mining engineering; (3) mechanical engineering; and (4) metallurgy. The problems of each group overlap to some extent those of the other groups, but the division adopted serves for a general consideration of the subject of mining. In this article particular attention will he de voted to mining as involving the problems of mining, engineering and mechanical engineering. These problems embrace the operations of dis covering and locating mineral deposits, of open ing the earth and excavating the ores, of trans porting the ores to the surface, and of handling mechanically the ores during their metallurgieal treatment. As. however, the handling of the ores preparatory to and during the processes involved in extracting the metals is of a different nature than mining proper and is frequently done at places far from the mines, these operations are considered in the article on OnE-DREssIxo and in the section devoted to in the articles on the various metals and the ad junct articles there mentioned.
PnosrEeTlxH. The search for and location of
deposits or veins of metal-bearing ores is called prospecting, and the men who perform this kind of work are called prospectors. The first proce dure in prospecting a tract of land suspeeted to contain mineral wealth is thoroughly to traverse it and to note carefully the familiar indications of the presence of minerals. These indications are often numerous in kind for each mineral and they also vary for different minerals. Generally speaking. coal, gypsum, salt, and simi lar minerals occur in unaltered deposits, that is, in rocks which have not undergone metamorphism, while the metallic minerals are found in rocks that have undergone 11101'e or less metamorphism. These are among the broad indications of the presence or absence of certain minerals. The geological age of the rocks is in respect to certain minerals a pretty certain indication whether these minerals are likely to be found or not. For example, the hulk of the coal deposits of the world has been found in rocks of the l'arbonif• crolis age; they exist in rocks of subsequent ages, but almost never in rocks of preceding ages. lle ferring, to specific indications, the prospector for coal will search for traces of smut or coal dust in the streams and water-worn banks, and for the presence of outcropping seams.
The presence of iron is indicated by mineral springs and rust-like stains of earth and rock. The presence or absence of vegetation may also indicate the existence of minerals; for example, a bed of phosphate rock is commonly indicated by a line of luxuriant vegetation and the outcrop of a mineral deposit by a lack of vegetation. Beds of magnetic iron are frequently located by their attraction for the magnetic needle. Placers arc fragmental deposits from water in which the heavier minerals have been concentrated in cer tain portions, usually next the underlying or bed rock. When prospecting for placers the prospee tor examines the country for the presence of any existing o• ancient watercourses in which de posits of placer material are likely to have been formed. Metallic gold and precious stones oceur frequently in placers. In prospecting for petro leum, natural gas, and bitumen, the surface indications looked for are springs of petroleum oil and naphtha; porous rocks saturated wit4i. bitumen or cracks i11 slate and other rocks filled with the same material ; springs, pools, or creeks showing bubbles of escaping gas or an iridescent coating of oil.