Feldspar Group
Feldspar are the most common rock forming minerals of the Earth’s crust Structure Classification Physical Properties Optical Properties Under PPL Under XPL Varities : Some advanced material Occurrance : Uses of feldspar :
GEO-ARTICLES
Amphibole Group
Amphiboles are the common constituents in both Igneous and Metamorphic rocks. General formula of Amphiboles is , W0-1X2Y5(Z8O22)(OH,F)2 Structure Amphiboles Classification Orthorhombic amphiboles Triclinic amphiboles Monoclinic amphiboles General Physical and Optical properties Physical Properties Optical properties
Speciation
a new species is created when a group of organisms within a species separates and develops unique characteristics. The new species is generally distinct from the original species and can no longer interbreed with it. ‘The process of transformation of species into new one with the accumulation of variations in time is known as speciation.’
Titanium deposits (Ti)
Important minerals Types of Deposits :- Indian occurances :- Process of extraction :- The mining is both manual as well as by hydraulic dredging. The beach sand after sun-drying is fed to electromagnetic and electrostatic separators in a processing plant for physical separation of various mineral constituents. Alteration :- Leucoxene is a fine grained alteration
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Crystal System and Their Identification
The crystallographic axes are the imaginary lines that we can draw within the crystal lattice. These crystal axis than works as the coordinate system within the crystal. These are well defined lines for the crystals. “On the basis of number of crystal axes and mutual relationship between them we define a crystal system“ Crystal system
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Crystal Forms
There are three elements of crystal forms. The face, edge and solid angle. Forms – It is a group of faces which have a like positions with respect to the crystallographic orientations. Forms may be classified in the following three ways – 1st way 2nd way 3rd way Simple form – when a crystal is
High Strain Textures
In the upper crust the pressure is less and brittle shear zone prevails whereas in the lower part pressure is enough to go for ductile shearing. Development of Textures
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High Strained Rocks
The shear zones is a region in the Earth’s crust where rocks are highly strained than the surroundings. These highly strained rocks can be found in the highly structural deformed terrains. These highly strained rocks can be cohesive or they can loose cohesion. These high strained rocks are classified on the basis of Cohesion, Foliation
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Replacement reactions (reaction rim/ corona)
In metamorphic petrology the reactions generally involves the replacement of minerals by their polymorphs and often the reactions may not complete. In many reactions, a pseudomorph may develop in which the new mineral retain the older minerals shape. “Some reactions produce intimate, typically wormy-looking intergrowths of two or more minerals called symplectite texture. Pseudomorphs may
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Carbonate Group
The carbonate mineral group form in the environment where water and carbon-di-oxide are present. The (CO3)– complex are basic building units of all carbonate minerals and are responsible for the properties to group. An acid test is widely used for identification of carbonates. Calcite Group (Hexagonal) Dolomite Group (Hexagonal) Aragonite Group (Orthorhombic) Calcite [CaCO3]Magnesite [MgCO3]Siderite