Lime or calcium.
Latin calx, calc‑, lime.
Calcium is the chemical element present in chalk, limestone, gypsum, and calcite. The adjectives calciferous and calcareous refer to minerals that contain calcium or lime. A calcicole (Latin colere, inhabit) is a plant that needs a soil containing lime. Calciferol (from calciferous plus ‑ol) is the formal name for Vitamin D, essential for metabolizing calcium in the body; conversely, calcitonin is a hormone that reduces calcium levels in the blood. The Latin word for a small stone, calculus, is used in medicine for a stone in the kidney or gall bladder; small stones were used as markers on Roman counting tables and the English mathematical terms calculate and calculus derive from this.