[Geography Notes] on Sorosilicate Pdf for Exam

Sorosilicate is an abundant type of rock-forming mineral that is found in the earth’s crust. They are the form of silicates. They are composed priorly with silicon and oxygen, coupled with other metals. a silicon-oxygen tetrahedron is the fundamental or core unit of these minerals.  These tetrahedra have a pyramid-like shape, complemented by small silicon cation (Si+4) which is in the center with four larger oxygen anions (O−2) which are present at the corners, this produces a net charge of negative 4 (−4).

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Minerals that are formed combined by two silicon-oxygen which is tetrahedra that shares oxygen atoms are called Sorosilicate. The double tetrahedra contain two silicon cations with seven oxygen anions, which give them a net charge of −6. The various metal cations thereby neutralize their charges between the double tetrahedra. 

The minerals existing in the sorosilicate group are quite rare, and they are also present in metamorphic rocks. Examples of sorosilicate which form during the process of metamorphism also formed during the process of crystallization of the igneous rocks, including those in the epidote group. 

Epidote has the formula of Ca2(Al, Fe) Al2O (SiO4) (Si2O7) (OH). This epidote group minerals consist of both the single and double silicon-oxygen tetrahedra. Yet another sorosilicate mineral is hemimorphite (Zn4(Si2O7) (OH)2·H2O). Hemimorphite is a secondary mineral, which means fan alteration product, this is found in the oxidized portions of zinc ore deposits.

Aluminum cations (Al+3) may substitute for silicon, and various anions such as hydroxyl (OH^–) or fluorine (F^–) may substitute for oxygen. In order to form stable minerals, the charges that exist between tetrahedra must be neutralized. This can be accomplished by the sharing of oxygen atoms between the tetrahedra, or by binding them together of the adjacent tetrahedra by various other metal cations. This further creates characteristics of silicate structures which can be used to classify the silicate minerals into cyclosilicates, inosilicates, nesosilicates, phyllosilicates, sorosilicate, and tectosilicates.

Sorosilicate Minerals

Sorosilicate is the silicate-type mineral that possesses isolated double tetrahedra groups with (Si2O7)6− or 2:7 if expressed in a ratio. This is often referred to as the double island group as there are two interlinked tetrahedrons that are isolated from all the other tetrahedrons.

Silicate minerals are minerals that are rock-forming, they are made up of silicate groups.  They are considered to be the largest and most important class of minerals which makes up approximately 90 percent of this planet’s crust.  

In the study of mineralogy, silica is known as silicon dioxide (SiO2) is usually considered to be a silicate mineral. Silica is found in natural substances as in the mineral quartz and its polymorphs.

On this planet Earth, this is a wide variety of silicate min in which the minerals occur in an even and a wider range of combinations which as a result of the processes forms and with re-working the crust for billions of years. These processes include the partial melting process, crystallization, fractionation, metamorphism, weathering, and also diagenesis. 

Living organisms here contribute to the geological cycle. Like for example, a type of plankton which is known as diatoms is constructed through their exoskeletons. The silica extracted from the seawater. The frustules of dead diatoms are the major constituent of sediment which is of a deep ocean and of diatomaceous earth. 

Pyrosilicates

A pyrosilicates is a typical chemical compound that is either an ionic compound that contains this anion called the pyrosilicates anion Si2O6−7, or this is an organic compound with the hexavalent ≡O3Si-O-SiO3≡ group. This anion is also called disilicate or orthosilicate.

Ionic pyrosilicates can be considered as salts of the unstable pyrosilicates acid, H6Si2O7. Unlike the acid, the salts can be quite stable. Indeed, pyrosilicates may occur widely in nature as a class of silicate minerals, specifically in the form of sorosilicate.

The pyrosilicates anion is described as two SiO4 tetrahedra which share a vertex (or an oxygen atom). The vertices are not shared as a negative charge each.

The structure of solid sodium which is a pyrosilicates was described by Volker Kahlenberg and others in 2010.