The name derives from Latin "calx" "lime", which was obtained from heating limestone. The term "caliche" is Spanish and is originally from the Latin "calx", meaning lime. The word calcar is derived from Latin "calx," meaning "heel". These two plays must happen within the calx. In those last few yards of the field is an area called the "calx". Calx, especially of a metal, is now known as an oxide. A sodium-calcium exchanger known as CalX pumps the calcium out of the cell. Calx is a substance formed from an ore or mineral that has been heated. "Calx" is also sometimes used in older texts on artist's techniques to mean calcium oxide.