>Widely used hard materials, e.g., alloys and ceramics, are often nonrenewable a...

		hammock on Oct 21, 2021 \| parent \| context \| favorite \| on: Hardened wood as a renewable alternative to steel ... >Widely used hard materials, e.g., alloys and ceramics, are often nonrenewable and expensive Alloys and ceramics are non-renewable? Aren't they pure mineral?