Dwarven Technology
Contrary to what Rino thought, the minecarts and rails used by dwarves were considered rather primitive. Back in his previous world, Rino knew that dwarves loved their metals to an unhealthy extent. Metal was considered stronger than stone because it was toughened by fire that could melt faces. They used something called 'steel' that was far superior to iron, and Rino swore they polished that metal daily because of its shiny appearance.
Here, the minecarts were not made out of steel. The body for transporting was made from wooden planks, while the wheels were carved out of stone. Thankfully, the dwarves did not fashion it completely out of wood and stone, or Rino would start questioning why they were even playing around with ores without using them.