Any process involved in the maintenance of an internal steady state of calcium ions within the cytoplasm of a cell or between mitochondria and their surroundings. [ GOC:mah GOC:ai ]
Synonyms: regulation of mitochondrial calcium ion concentration regulation of calcium ion concentration in mitochondria regulation of calcium ion concentration in mitochondrion calcium ion homeostasis in mitochondria calcium ion homeostasis in mitochondrion mitochondrial calcium ion concentration regulation