Mineral, accessory primary

In the leaching process, bacteria such as Thiobacillus ferroxidans and those belonging to the Sulfolobus genera, play a major role in the oxidation reactions at moderate and higher temperatures respectively. The oxidation of sulfides by bacteria is typified by the reactions of pyrite, a common accessory mineral in primary copper ore bodies this reaction can be considered to proceed through two stages ... 

Recent studies on iron sulfide minerals in coals, minerals in coals, and in situ investigation of minerals in coal all used the scanning electron microscope (SEM) as the primary analytical tool. The ion microprobe mass analyzer (IMMA) is more sensitive than either the energy-dispersive x-ray spectrometer or the wavelength-dispersive x-ray spectrometer, both of which are used as accessories to an electron microscope. 

Table 7.2 shows some examples of primary minerals. Feldspars are among the most important and prevalent primary minerals in soils they are common in the sand and silt fractions of soils and can also be found in the clay fraction. Metamorphic rocks also contain feldspars. K feldspars are important sources of K in soils (Sparks 2002). Pyroxenes and olivines are some of the accessory minerals found in the high-density fraction. Olivines are green nesosilicates in which Mg + and Fe " are... 

Dominant ore minerals in the reduced zone are pitchblende and coffinite and, in some deposits, associated primary vanadium oxides—for example, montroseite. In oxidized zones the important uranium minerals are the uranyl vanadates (carnotite, tyuyamunite or francevillite). Accessory elements include Mo, Se and Cu. Average uranium content ranges from 0.01 to 0.40 7o U3O8. 

Organic nutrients also include vitamins. Inorganic chemical compounds, such as dietary minerals, water (and oxygen), may also be considered nutrients. Vitamins and dietary minerals are collectively known as accessory (additive) nutrients and are often referred to as essential nutritional factors. With the exception of some vitamins that humans cannot synthesise, these accessory nutrients must be obtained from foods. They are therefore known as exogenous factors. Another essential nutrient is water, which is obtained in small amounts by oxidation of primary nutrients, but in much larger quantities from foods, and especially from beverages. Most foods contain a mixture of some or aU of the nutrient classes, together with many other substances. Some nutrients can be stored internally (such as the fat soluble vitamins), while others are required more or less continuously. Poor health maybe caused by a lack of required nutrients or, in extreme cases, too much of a required nutrient. 

Chlorite is a common accessory mineral in low-to-medium grade regional metamorphic rocks and may be the most abundant mineral in metamorphic rocks of the chlorite zone. It is an occasional constituent of igneous rocks, in most cases probably forming secondarily by deuteric or hydrothermal alteration of primary ferromagnesian minerals, such as mica, pyroxene, amphibole, garnet, and olivine. Chlorite is found in pegmatites and fissure vein... 

In geological formations, the content of heavy minerals may vary from 0 to 100%, and there is a tendency for some heavy mineral species to occur preferentially in certain kinds of rock. In any rock the minerals may be divided into primary and secondary rock minerals according to their origin. Primary rock minerals were formed at the same time as the rock containing them, while secondary rock minerals were formed as a result of reactions taking place within the host rock at some time after its formation. Rock-forming minerals may also be classified as essential or accessory. Essential minerals are those implied in the definition of the rock name, while accessory minerals are additional to the above definition, so that their absence would not necessitate a change in the rock name. Heavy minerals as they occur in rocks may be essential or accessory they are usually primary, but occasionally they are secondary. 

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