Ore grade is a measure that describes the concentration of a valuable natural material (such as metals or minerals) in its surrounding ore. Ore grade is used to assess the economic feasibility of a mining operation: the cost of extracting a natural material from its ore is directly related to its concentration, and the cost of extraction must be less than the market value of the material being mined for the operation to be economically feasible. In chemistry, a metal (Greek: Metallon) is an element that readily forms ions (cations) and has metallic bonds, and it is sometimes said that it is similar to a cation in a cloud of electrons. ... Minerals are natural compounds formed through geological processes. ... An ore is a mineral deposit containing a metal or other valuable resource in economically viable concentrations. ... The El Chino Mine located near Silver City, New Mexico is an open-pit copper mine Mining is the extraction of valuable minerals or other geological materials from the earth, usually (but not always) from an ore body, vein, or (coal) seam. ...

Ore grades are usually expressed as an amount of material per ton (or tonne) of ore. The ore grade required for economic feasibility varies widely based on the value of the material being mined. For example, the Argyle diamond mine in Australia produces diamonds out of ore graded at 7 carats (1.4 grams) per tonne, or about 1.4 parts per million, at a value of about 7 USD per carat or 35 USD per gram (the Argyle mine is considered to have high ore grade, but low value per carat, when compared to other diamond mines) [1] (http://www.goldismoney.info/forums/showpost.php?p=6226&postcount=3). Conversely, zinc mines may require an ore grade of 8% or more by total weight to be economically feasible [2] (http://66.102.7.104/search?q=cache:e-ydt9-GD3MJ:minerals.usgs.gov/minerals/pubs/commodity/zinc/720496.pdf+%22Copper+mine%22+%22ore+grade%22+%22economically+feasible%22&hl=en), as zinc currently trades at prices of about 1100 USD per ton [3] (http://www.arcon.ie/s/ZincPrice.asp). These data indicate a diamond value at the Argyle mine of about 50 USD per tonne of ore, and zinc value at a hypothetical 8% ore grade mine of about 90 USD per ton of ore, showing the similarity of economic reward for a similar amount of mining effort (although other extraction costs do factor in and may differ considerably). The word ton or tonne is derived from the Old English tunne, and ultimately from the Old French tonne, and referred originally to a large cask with a capacity of 252 wine gallons, which holds approximately 2100 pounds of water. ... A tonne (also called metric ton) is a non-SI unit of mass, accepted for use with SI, defined as: 1 tonne = 103 kg (= 106 g). ... The Argyle diamond mine is a diamond mine located in Australia. ... Meanings of Carat or Karat: Carat is a unit of mass for gems. ... For other meanings of gram, see gram (disambiguation). ... Parts per million (ppm) is a measure of concentration that is used where low levels of concentration are significant. ... The United States dollar is the official currency of the United States. ... General Name, Symbol, Number zinc, Zn, 30 Chemical series transition metals Group, Period, Block 12, 4, d Density, Hardness 7140 kg/m3, 2. ...