Ashtadhatu is a combination of eight metals. The metals used are gold, silver, copper, zinc, lead, tin, iron and mercury. There are also Ashtadatu Yantras. Ashtadhatu Idols (Murtis) are found in many temples in India
The picture is that of an Ashtadhatu idol of Lord Krishna seized by police from Delhi
The process of making Ashtadhatu idols is bit complex and it varies.
In the first stage, the exact model of the deity is made using wax.
In the second stage, the wax model is covered with clay to make a mold.
In the third stage, the wax and clay mold is put into fire. In this process, the clay hardens and the wax melts away making a hollow mold.
In the fourth, the eight metals – taken according to the proportion required – are melted.
In the fifth stage, the melted amalgam is poured into the clay mold and is allowed to cool.
In the final stage, after cooling, the clay molds are dismantled and the Ashtadhatu idol is revealed.