The name of the block is "Copper Block", which is inconsistent with all other mineral block names (besides "Lapis Lazuli Block"). I'm not sure whether this was an oversight.

Solutions:

• Rename Copper Block to Block of Copper (and optionally Lapis Lazuli Block to Block of Lapis Lazuli)
• Rename all other mineral blocks to "materialtype Block" - would help them to fit in better with their namespaced IDs as well as other English translations