Which of the following is Incorrectly matched.

• A

  Mica- ${\mathrm{K}}_2\mathrm{O}.3{\mathrm{Al}}_2{\mathrm{O}}_3.6{\mathrm{SiO}}_2.2{\mathrm{H}}_2\mathrm{O}$

• B

  $\text{ Beryl- }3\mathrm{BeO}\cdot {\mathrm{Al}}_2{\mathrm{O}}_3\cdot 6{\mathrm{SiO}}_2$

• C

  $\text{ Cryolite - }2\mathrm{NaF}\cdot {\mathrm{AlF}}_3$

• D

  $\text{ Corrundum - }{\mathrm{Al}}_2{\mathrm{O}}_3$