in the depth of the earth. Moreover, according to Schmitt et al., in the year 1950 [1], there are cases of same kind of alterations arising due to movement of hydrothermal solutions close to the surface. Water of hot spring at Yellowstone Park altered rocks (volcanic) into calcite and zeolites, orthoclase and quartz, and kaolinite and beidellite containing rocks.
2.2 Comparitive Stability of Minerals on the Basis of Their Sequence of Weathering
Depending on the factors initiating the chemical weathering process, weathering of minerals depends on their stability. Owing to the stability some gets weathered slower and some faster in comparison to other minerals. The process of weathering of minerals depending upon their stability is occurring in a sequence, often referred as weathering sequence. Establishment of sequence of weathering process occurs on the basis of certain criteria, comparative persistence with depth of formation, age of formation, size of particle, intensity factors of weathering, and geographical factors.
2.2.1 Heavy Minerals
According to Pettijohn et al., in the year 1941 [28–30], reported rocks whose age was increasing included decreasing quantity of higher specific gravity minerals having less stability. Hence, among rocks which are older in comparison to Pleistocene, olivine was not included. The weathering sequence given by Pettijohn in the order of increasing order of stability includes (most unstable mineral first), olivine (22), actinolite (21), diopside (20), hypersthene (19), sillimanite (18), augite (17), zoisite (16), sohene (15), topaz (14), andalusite (13), hornblende (12), epidote (11), kyanite (10), staurolite (9), magnetite (8), ilmenite (7), apatite (6), biotite (5), garnet (4), monazite (3), tourmaline (2), zircon (1), rutile (−1), muscovite (−2), and anatade (−3). The last three minerals with negative numbers shows formation tendency instead of disappearance at the time of prolonged burial. According to Weyl et al., in the year 1952 [1], it was suggested to classify four groups of heavy minerals according to their relative stability. The very stable group included magnetite titanite, rutile, zircon, and tourmaline. The slightly stable group included epidote and garnet. The most unstable minerals included augite, hot blende, and olivine. The above discussion shows way how heavy minerals stability could be used for establishing rock formation age, out of which soil was formed.
2.2.2 Coarsely Grinded Minerals
According to Goldich et al., in the year 1938 [31–33], stability sequence of coarsely grained minerals was reported as (most stable first) quartz, muscovite, orthoclase, plagioclase, biotite, amphibole, and pyroxene. Marel et al., in the years 1949, 1948a, and 1947 [34–36] reported magmatic minerals stability, keeping the particle size and weathering conditions similar (most resistant first), quartz, tourmaline, rutile, staurolite, zircon, allanite, albite, microcline, orthoclase, garnet, muscovite, oligodase, andesine, bytownite, epidote, anorthite, ampjibole, augite, biotite, hypersthene, olivine, and volcanic glass. As coarsely grinded quartz is not susceptible toward weathering, it is considered as stable among all the minerals.
2.2.3 Clay Size Mineral Particles
When the size of the particles of mineral becomes finer, then the sequence of stability of mineral becomes different relative to the coarsely grinded particle of mineral. This happens due to the enhancement of specific surface which increases the process of mineral weathering, which was comparatively more stable in coarsely grinded particle size. The particle size of clay minerals is below 200 diameters. According to Jackson et al., in the year 1948 and 1952 [37–39], the sequence of weathering consisted of 13 stages for clay size particles. The sequence is in descending order of stability:
Anatase (corundum, leucoxene, ilmenite, rutile, zircon, etc.)
Hematite (limonite, goethite, etc.)
Gibbsite (also allophane, boehmite, etc.)
Kaolinite
Montmorillonite (also saponite, beidellite, etc.)
Vermiculite and silicates interstratified 1:2 layer
Muscovite (also illite, sericite, etc.)
Quartz
Albite (also orthoclase, microline, stilbite, anorthite, etc.)
Biotite (also nontronite, antigorite, magnesium chlorite, glauconite, etc.)
Olivine-hornblende (also diopside, pyroxenes, etc.)
Calcite (also apatite, aragonite, dolomite, etc.)
Gypsum (also ammonium chloride, sodium nitrate, halite, etc.)
There are few modifications in the above list. Apatite was included at calcite stage; allophane was included in gibbsite stage by Tamura et al., in the year 1953 [40–42]. Marel et al., in the year 1947, and Haseman and Marshall, in the year 1943 [43–45], included zircon in Anatase stage. Woof and Carroll et al., in the year 1951 [46–48], and Marsden and Tyler, in the year 1938 [49–51], included leucoxene in the Anatase stage.
2.3 Factors Affecting the Rate of Chemical Weathering
The rate of reaction involved in a chemical weathering is under the control wide range of capacity and intensity factors, acting as function of integration of capacity, intensity, and time. The weathering time can give rise to stage or degree of weathering. The various driving force affecting the rate of reaction involved in chemical weathering can be recognized to a extent of consideration for formation of soil are five usual factors including, time, parent material, relief, biotic forces, and climate. The conditions affecting the reaction rate of chemical weathering needs to be analyze more specifically in categories other than above listed five factors for formation of soil. Leaching effect is included in single intensity factor whether it is under the control of internal drainage, relief, rate of evaporation, distribution of rainfall, and amount of rainfall. The extent as well as the nature of leaching is collectively significant for determining the process of chemical weathering. Reduction and oxidation are specifically considered whether controlled by valence of the ions in the minerals, texture of the material, etc.
2.3.1 Capacity Factors Which Controls the Reaction Rate of Chemical Weathering
2.3.1.1 Specific Surface Role
The higher the specific surface area of the targeted mineral, the finer the size of the particle and hence very speedily it gets affected by chemical weathering processes as reported by Polynov et al., in the year 1937 [5], and Merrill et al., in the year 1906 [2]. The enhancement of the specific surface is inversely proportional to the material particle diameter. It has been reported that sequence of weathering are different in case of particle with fine size in comparison to that of coarsely sized particles. For example, due to effect of specific surface the rate of weathering of volcanic ash is faster in comparison to lava. This happens due to the larger surface area subjected for processes for weathering.
2.3.1.2 Specific Weatherability Role of Mineral
According Jackson et al.,
