Gurmeet Singh posted an Question
November 09, 2020 • 20:59 pm 30 points
  • IIT JAM
  • Geology (GG)

A five-fold axis of symmetry is present in: a quartz c. tourmaline b. riebeckite d. none of these.

A five-fold axis of symmetry is present in: A Quartz C. Tourmaline B. Riebeckite D. None of these (BHU-2010)

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    Sajan sarthak Best Answer

    5 fold generally doesn't exist Quartz hexagonal system crystallization so 6 fold. tourmaline also 6 fold , and ribeckite monoclinic so 1 fold

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    Rahul kumar best-answer

    Answer (D) None of these Five fold axis of symmetry doesn't exist in any crystal because five fold axis of symmetry can't produce a complete crystal lattice upon repetition. In nature, crystal can only have one, two, three, four and six fold axis of symmetry. So, all the given options (Quartz, tourmaline, riebecklite) are wrong because minerals can never have five fold symmetry.

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