Ropes are no longer used in build requirements, they were replaced by Bones or Wooden Buckets, see screenshots below for current requirements.
June 8, 2018 Update • Mine changes:
Mine production timer decreased from 2h to 1.5h
The Mine is available for purchase at L14.
It gives rocks every 1.5h - timer decreased and payout increased by enchanting and +1 if you allow a neighbor to harvest it for you.
You must reach a certain Magic Level in order to upgrade
Copper Nuggets Drop Randomly from any level mine on your land or @Neighbors
Precious Stones will only drop from your L3+ Mine or Large Mine