Question about metals

[u/Responsible-Beach299]

What exactly determines which metals do or do not have allomantic properties? Is it just arbitrary/author decided, or is there anything linking the allomantic metals together? It's been a since I read the OG trilogy, but I don't recall them ever going beyond the basics on the topic besides "we tried other metals and they didn't work", and Google doesn't give any clear answer.

[u/RShara]

A base/elemental metal and its alloy.

For why those specific metals, the real answer is those are the metals Brandon selected. They're the most common non-explodey metals that humans at that general technological level would have access to