Secondary minerals definition

The clay fraction, which has long been considered as a very important and chemically active component of most solid surfaces (i.e., soil, sediment, and suspended matter) has both textural and mineral definitions [22]. In its textural definition, clay generally is the mineral fraction of the solids which is smaller than about 0.002 mm in diameter. The small size of clay particles imparts a large surface area for a given mass of material. This large surface area of the clay textural fraction in the solids defines its importance in processes involving interfacial phenomena such as sorption/desorption or surface catalysis [ 17,23]. In its mineral definition, clay is composed of secondary minerals such as layered silicates with various oxides. Layer silicates are perhaps the most important component of the clay mineral fraction. Figure 2 shows structural examples of the common clay solid phase minerals. 

That the atomic weight of uranium lead is extremely variable has already been shown. In order to interpret this variability its sources must be studied both geologically and mineralogically. On the geologic side of the question the uranium ore can be divided in to three principal classes, which are sharply distinct. The definitely crystallized varieties of uraninite occur in coarse pegmatites, associated with feldspar, quartz, mica, beryl, and other minor accessories. The massive pitchblende is found in metalliferous veins, together with sulphide ores of copper, lead, iron, zinc, and so forth. As for camotite, that is a secondary mineral, found commonly as an incrustation on sandstone, and often, also upon fossil wood. There may be other modes of occurrence, but these are the most distinctive. 

The word clay has ambivalent definitions (Bergaya, 2000). On the one hand it is used to define any soil particle smaller than 2 pm, but on the other hand it includes a large group of microcrystalline secondary minerals based on hydrous aluminum or magnesium silicates that have sheet-like structures (Manahan, 2000). There are at least two points that make clay minerals so active in natural processes, and became the key for their wide applications (a) The very large surface area that arises from the tiny size of the particles (nano-scale), and... 

Pseudomorphism is the change of the original chemical composition of a substance into some other equally definite compound by the action of natural agencies Pseudomorphism exists when the external crystalline form of a mineral is inconsistent with its internal chemical composition and atomic structural arrange mem. It is always a secondary process. The altered substance is known as a psetuhmiorpb. 

Paraffin followed by candelilla wax and microcrystalline waxes, and eventually by beeswax, are considered as the most effective moisture barriers derived from edible waxes (Morillon et al. 2002). There is no satisfactory chemical definition for the term wax which is used for a variety of products of mineral, botanical and animal origin that contain various kinds of fatty materials (Table 23.4). The term resins or lacs can also be used for plant or insect secretions that take place along resins ducts, often in response to injury or infection, and result in more acidic substances (Hernandez 1994). However, all waxes tend to contain wax esters as major components, that is, esters of long-chain fatty alcohols with long chain fatty acids. Depending on their source, they may additionally include hydrocarbons, sterol esters, aliphatic aldehydes, primary and secondary alcohols, diols, ketones, triacylglycerols, and so on. 

Any mineral with a particle size of < 2 m is, by definition, part of the clay fraction of a soil. However, the term clay mineral has a different connotation historically, usually referring to the secondary layer silicates, which are the dominant inor-... 

There is no consistent definition for the use of the term phosphorites. Suggestions reach from a limiting P content of 6 wt.% (van Cappellen and Berner 1988) to a threshold value of 18 wt.% P O, as representative for authigenic and biogenic phosphate minerals (Jarvis et al. 1994). However, the formation of secondary P phases from initially more labile-P in marine sediments (see above) is one major sink for phosphoms on Earth, because this general process results in sequestration of P from the nutrient cycle in the water column (e.g. Compton et al. 2000). 

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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