The percentage of metals used is 4 portions of silver, 1 portion of gold, 8 portions of brass, 8 portions of copper and a small quantity of iron. This percentage is only to give a general idea and might vary from region to region.
Today, the main constituent in Panchaloha idol is copper, brass and lead. Large quantity of copper is mainly used in idols that are sold in large-scale like the Nataraja statue.
But the idols made for temples strictly follow the tradition and contain gold and silver.