In this chapter, unless the context otherwise requires,

(1) “gross income from property” means the gross income from mining in the state;

(2) “mining” means an operation by which valuable metals, ores, minerals, asbestos, gypsum, coal, or stone, or any of them are extracted, mined, or taken from the earth; “mining” includes the ordinary treatment processes normally applied by mine owners or operators to obtain the commercially marketable product, but does not include the extraction or production of oil and gas, marketable earth, quarry rock, or sand and gravel;

(3) “net income of the taxpayer (computed without allowances for depletion) from the property” means the gross income from the property, less allowable deductions attributable to the mineral property upon which the depletion is claimed and the allowable deductions attributable to ordinary treatment processes insofar as they relate to the product of the property, including overhead and operating expenses, development costs properly charged to expense, depreciation, taxes, losses sustained, etc., but excluding allowances for depletion, and deductions for federal income taxes, or for the tax imposed by this chapter;

(4) “new mining operations” means mining operations which began production after January 1, 1953, or which have not been liable to pay a mining license tax under this chapter on net income since January 1, 1948;

(5) “ordinary treatment processes” includes

(A) in the case of coal: cleaning, breaking, sizing, and loading for shipment,

(B) in the case of sulphur: pumping to vats, cooling, breaking, and loading for shipment,

(C) in the case of iron ore, bauxite, ball and sagger clay, rock asphalt, and minerals which are customarily sold in the form of crude mineral product: sorting, concentrating, and sintering to bring to shipping grade and form, and loading for shipment, and

(D) in the case of lead, zinc, copper, gold, silver, platinum metals or fluorspar ores, potash and ores which are not customarily sold in the form of the crude mineral product: crushing, grinding, and beneficiation by concentration (gravity, flotation, amalgamation, electrostatic, or magnetic), cyanidation, leaching, crystallization, precipitation (but excluding electrolytic deposition roasting, thermal or electric smelting or refining), or by substantially equivalent processes or combination of processes used in the separation or extraction of a product from the ore, including the furnacing or quicksilver ore;

(6) “production” means the date on which the initial shipment of products from mining operations is made.