The process or business of extracting from the earth the precious or valu- able metals, either in their native state or in their ores. In re Rollins Gold Min. Co. (D. C.) 102 Fed. 985. As ordinarily used, the term does not include the extraction from the earth of rock, marble, or slate, which is commonly described as “quarrying,” although coal and salt are “mined;” uor does it include sinking wells or shafts for petroleum or natural gas, unless expressly so declared by statute, as is the case in Indiana. See State v. Indiana, etc., Min. Co., 120 Ind. 575, 22 N. E. 778, 6 L. R. A. 579; Williams v. Citizens’ Enterprise Co., 153 Ind. 490, 55 N. E. 425.