Is tin a metal non metal or metalloid?

Tin has two forms (allotropes) one is "white tin" (beta-tin) which is a metal although some chemists/metrial scientists would call it a "poor metal"- and "grey tin" (alpha-tin), a low temperature form, which has a similar structure to diamond and more covalent in character. So one allotrope is a metal and the other isn't. Probably the answer a school teacher expects is tin is metal.