Prince Rupert's metal

An alloy of lead, antimony, and mercury, made for sheathing ships.

(obsolete) gold

The metal from which iron pots are made, different from common pig iron. / An alloy of copper with lead used for making large vessels for various purposes in the arts.

The fused material for making glass.

Muntz metal

Muntz metal / (UK, auctions) Gold (or some alloy of gold) that cannot be labelled as gold in the UK because it does not bear an Assay Office mark.

Hard dark stone crushed into small pieces used in surfacing roads, for ballast in railway tracks, etc.; gravel; blue metal.

(programming) A runtime environment where little to no abstraction is available: usually employing a low-level programming language, without access to any operating system facilities, and interfacing hardware directly.

A subgenre of heavy metal music, often with anthem-like songs with fantasy-based subject matter and a strong, dramatic chorus.