unmineable

Unmineable describes resources—typically minerals, coal, or ore deposits—that cannot be extracted profitably or safely given current technology, economics, or conditions.

A seam may be unmineable because it's too thin, too deep, or the surrounding rock too unstable: The geological survey declared the deposit unmineable.

In cryptocurrency contexts, unmineable refers to coins that cannot be obtained through computational mining, only through other means like staking or purchasing.