Ore: The word ore has been derived from the Middle English, oor, because of its similarity to earlier names for copper ore and brass. Ore is defined as a naturally occurring mineral or aggregate of minerals from which metal/metals could be extracted with profit. It usually occurs with useless gangue mineral or mineral aggregates, substance or unwanted substance. In simplified words, we can define ore as an aggregation of one or more ore minerals and gangue from which one or more metals are extracted profitably. After their mining the ores are further processed to extract the elements of interest from the waste rock and from the ore minerals.
Ore deposits or mineral deposits are natural concentrations of useful minerals or rocks, which can be economically exploited. Concentrations that are too small or too low-grade for mining are called occurrence or mineralisation (Pohl, 2011). The definition of ore deposits includes ores of metals and non metals, industrial minerals, gemstones, rocks used as aggregate for building stone and coal and oil shale.
Ore bodies: The ore deposit consists of the rock bodies or ore bodies enclosing one or more ore minerals along with those natural materials which are not ore. Not all the ore within the ore body will be extracted. Ore bodies are divided into reserves and resources.
Gangue: It is the commercially worthless material that surrounds or is closely mixed with wanted mineral in an ore deposits. Let us read about the difference between ore and gangue. Minerals with high percentage of metal, that can be profitably extracted is known as ore. The term gangue refers to the impurities like sand, soil that are removed from the ores.
Reserves are ore that are economically feasible to mine and for which there are no
legal or engineering impediments to mining.
Resources are ores that may potentially be extracted at sometimes in the future.
Industrial minerals: They have been defined as any rock, mineral or other naturally occurring substance of economic value, exclusive of metallic ores, mineral fuels and gemstones (Noetstaller, 1988). The non-metallic minerals are considered as industrial minerals rather than ores. Thus, galena (PbS) is an ore mineral, while halite (NaCl) and phosphorite or rock phosphate (Ca5FO12P3) are industrial minerals. Many other minerals are mined for industrial uses, namely cement, building stone, abrasives, fertilisers, fillers, fluxes, ceramics, glasses, etc. They are classed as industrial minerals. Although practically all industrial minerals contain metallic elements and they are often confused with non-metallic. Many metallic ores, such as bauxite, ilmenite, chromite and manganese minerals are also considered important raw materials for industrial minerals.
Host Rock: It is the rock which surrounds or encloses ore deposits and like gangue it has no commercial value.
Tenor: It is the actual metal content present in an ore. Tenor in case of non-metallic minerals refers to the percentage of metal content in an ore mined, whereas in case of metallic minerals, it signifies metal content in an ore mined.
Ore Grade: The term ore grade is used in the commercial classification of ores which takes into account the chemical and physical properties of an ore. It is usually expressed as percentage or parts per million (ppm) for metal contents, e.g. Cr2O3 in chromite ore, WO3 in tungsten ore and P2O5 in apatite and rock phosphate. While penny weight, troy ounce, gram per unit weight is used for precious minerals. Ore grade is also an expression of the quality of the deposit.
Specification: It is another important term which is related with the grade. It focuses on the Tolerance limits of all constituents present in it and depends upon:
Technique of manufacturing process adopted by individual units; and
Grade of other raw material required to be used as whole or to obtain the end product.
Technique of manufacturing process adopted by individual units; and
Grade of other raw material required to be used as whole or to obtain the end product.
Beneficiation: It refers to improving the quality of an ore mineral before feeding smelting or other operations. Different physical or chemical methods are used to separate the gangue or undesired minerals from the ore minerals.
Ore magma: This term is used for the abnormally rich magma that crystallises out into
an ore most often in case of sulphide or oxide ore minerals.
Ore guides: The final aim of the geologist is to detect subsurface ore bodies. The exploration for ore bodies is often done with the help of ore guides. Thus ore guides are structural or other features and conditions which serve as clues to the location of ore body. The most practical and definite type of guides are those that are capable of representation on maps, sections or models. The ore guides include geological, geochemical, botanical and biogeochemical observations or even biotic activity that provides clue about sub-surface mineralisation.
Ore genesis: The ore deposits are formed by variety of geological processes and the process of their formation is called ore genesis.
Ore shoot: This term is commonly used in mining operations. These are relatively rich portions of mineralised body.
Ore microscopy: Most of the metallic ores are opaque. Therefore study of ore requires a specially designed microscope called as ore microscope, where polished ore sections or slabs are studied under the microscope in a reflected light.
Gossan: They are signboards that point to what lies beneath the surface. The word ‘gossan’ is a Cornish word and is used to designate the oxidised outcropping comprising cellular mass of limonite. The outcropping of cellular mass of limonite or capping is the leached upper part of a rock body that contains disseminated sulfide minerals.
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