Thread:Cimeex/@comment-7763430-20191214111359/@comment-31225999-20191214212342

I have not found other Abandoned Ruin drops for Unknown Recipe in the game's database except the one inside Parts Boxes.

By random quarrying do you mean digging stone/ore patches? I don't believe I have seen any of them drop an Unknown Recipe, though they do drop other items except stone and ores. You can check out these items and their chances from the database on every Abandoned Ruin page in Ores section if you're curious.