Formation
(1) Metamorphic, through regional or contact metamorphism of calcium-rich rocks (e.g., marl or basic magmatic rocks) under low to medium P-T conditions (green schist to amphibolite facies).
(2) Hydrothermal, as a transformation product of plagioclases (saussuritization) or in fissures and veins through alteration of calcium-bearing silicates.
