Linked from
The 14 pages that link to Aragonite, each with the reason it gives.
LimestoneRelated: Some marine shells begin as aragonite before becoming calcite or dissolving.
TravertineRelated: Some travertine deposits contain aragonite alongside or instead of calcite.
Gastropod shellRelated: Many gastropod shells use aragonite as a major mineral component.
PearlRelated: Its crystals form much of the mineral phase in nacreous pearls.
Mollusc shellRelated: Many shells use aragonite as a mineral phase, alongside or instead of calcite.