Ishita Das posted an MCQ
January 21, 2021 • 18:28 pm 30 points
  • IIT JAM
  • Geology (GG)

Coesite, a high pressure polymorph of quartz is found in rocks exposed on earth's surface because

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    Sajan sarthak best-answer

    MAY BE OPTION D IS CORRECT BUT I FOUND MOST APPROPRIATE IS OPTION C ....BELOW IS A GRAPH OF QUARTZ POLYMORPH YOU CAN SEE THE PRESSURE AND TEMPERATURE RANGE MUST BE VERY MUCH HIGH INORDER TO TRANSFORM COESITE TO STISHOVITE...SO AT THE SURFACE THE FEASIBILITY IS VERY LESS FOR THAT.

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    Sajan sarthak Best Answer

    Coesite and stishovite have a higher density than the low pressure polymorphs, in particular stishovite, which has a specific density of 4.29 g/cm3. While Coesite is still made of interconnected SiO4 tetrahedra, stishovite assumes a completely different arrangement of atoms in its crystal lattice.

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    didn't get why can't it be option d

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