Source : Webster's Revised Unabridged Dictionary (1913)

Aragonite \A*rag"o*nite\, n. [From Aragon, in Spain.] (Min.)
   A mineral identical in composition with calcite or carbonate
   of lime, but differing from it in its crystalline form and
   some of its physical characters.

Source : WordNet®

aragonite
     n : a mineral form of crystalline calcium carbonate; dimorphic
         with calcite