Aragonite

Aragonite is a form of calcium carbonate, one of three polymorphs of CaCO3 alongside calcite and vaterite, and Wikipedia says it forms through both biological and physical processes. Its colour varies, commonly red or white, and its Mohs hardness is 3.5 to 4. Wikipedia also names a branching form called flos-ferri. Hall lists white, yellow, gold, green, blue and brown, calls it an earth-healer and grounding stone attuned to the Earth Goddess, and associates it with centring, patience and strength. She suggests placing it under a pillow to ease restlessness. Cunningham has no entry for it. These uses are Hall's claims, not tested properties of the mineral.