Aragonite is chemically the same as calcite (CaO3) but is less common and forms crystals of different shapes.
It is slightly harder and heavier than calcite and does not cleave as distinctly. It is white, grey, or cream in colour.
The mother of pearl lining of sea shells is aragonite. Coral and ammonites formed by plants and animals in warm seas are also aragonite.
This aragonite, flos ferri, is a branching growth of pure white aragonite.