Crucible

In chemistry, a crucible is a kind of laboratory apparatus[?] that is usually a cup, made of porcelain or an inert metal, used to heat chemical compounds to very high temperatures. One of the earliest uses of platinum was as a material in crucibles, and metals such as nickel and zirconium are used as crucible materials these days.

Reference:

• Metal Technology - a manufacturer of crucibles (http://www.b-jenterprises.com/AboutUs.htm)