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Nilanjan Bhowmick AIR 3, CSIR NET (Earth Science)
- IIT JAM
- Geology (GG)
Cross hatched twinning in microcline is due to
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Sajan sarthak Best Answer
Order - Disorder Transformations - these involve the state of order or disorder in a crystal structure. Perfect order can only occur at a temperature of absolute zero (-273oC). As temperature increases, the degree of order or randomness of a crystal structure decreases, so that the higher temperature forms of minerals are more disordered than the lower temperature forms. Because the state of order-disorder changes gradually with increasing temperature, there is no definite temperature at which a transformation occurs. An example of polymorphic transformations that involve order-disorder is the compound KAlSi3O8. At high temperature the stable form is Sanidine (Monoclinic). At lower temperature the structure changes to one of orthoclase (also Monoclinic), and at even lower temperature the structure becomes that of the more ordered structure of microcline (also Triclinic). In simple crosshatch is a twining seen in microcline due to order disorder a variety of polymorphic transformation
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Rahul kumar![best-answer]()
Answer (A) Polymorphic transformation Microcline characterized by cross-hatch twinning that forms as a result of the transformation of monoclinic orthoclase into triclinic microcline. Both Microcline and Orthoclase is KAlSi3O8, and polymorphic transformation of Orthoclase into Microcline gives rise to cross-hatched twinning.