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The main constituents of pearls are

  • A.Calcium oxide and ammonium chloride
  • B.Calcium carbonate and magnesium carbonate
  • C.Silica and alumina
  • D.Ammonium sulphate and sodium carbonate

Answer: B

Pearl is composed mainly of calcium carbonate with some magnesium carbonate, laid down by the oyster in thin concentric layers.

The carbonate is deposited as aragonite platelets bound by the protein conchiolin, and it is interference of light between these layers that produces a pearl's lustre.

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