Isn't metal a sub genre of rock?
Wikipedia technical info: Pewter is a malleable metal alloy, traditionally 85–99% tin, with the remainder consisting of copper, antimony, bismuth and lead. Copper and antimony act as hardeners while lead is common in the lower grades of pewter, which have a bluish tint. It has a low melting point, around 170–230 °C (338–446°F), depending on the exact mixture of metals.[1] The word pewter is probably a variation of the word spelter, a colloquial name for zinc.[2]. It is really nice to work with because its melting point is so low. You can solder it with a tiny flame or create a mold and cast it easily. One can combine it with copper, I know, because I created brooches this way. It forms easily, almost by bending with the hand. You must keep Pewter tools, soldering rocks, flux, etc. separated from silver, gold, other metals, tools...
Traditionally a metal alloy composed of 85% to 99% tin.
