The programmer art textures for gold and iron nuggets use the same base, but are coloured differently with the iron nugget being rotated 90 degrees to the left.
The gold nugget has been changed in the texture update with the iron one being left out though, outdated. It would be cool if the Iron nugget was updated to the new standards too and maybe in the same way - use the gold nugget as a base, recolour it to the iron palette and rotate it 90 degrees to the left.

Made an example (marked green) and a comparison of the current textures in the attachments.