While I like the idea of having the tiny pebble sink for stoking in mining, it frustrates me incredibly that it seems to randomly and unfavourably pick whatever it uses the turn on. I know it also speeds things up, but the biggest win is that you only need 4 ores to smelt something down, instead of 5. Which is especially useful for the rarer ores such as gold and chaosium.
I've had it happen on multiple occasions that my stoke turns were wasted on moonstone ores (which only require 1!) or ores that were available in multiples of 5, only for 4 chaosium or gold ores the remain in my cart unsmelted. I would love it if the system behind it was a tad smarter and focused first on reducing the rarer ores of which there are no multiples of 5 available. Or to give us the opportunity to choose which ores to use the stoking on.
Example: I had 14 mithril, 4 gold, 4 chaosium, 5 lorium and 2 moonstone shards in my cart. I had 4 stoke turns left from the previous round. When I returned to my furnace, instead of using the stoke turn on the chaosium, it wasted 2 stoke turns, one on a moonstone shard and 1 on lorium (of which I had 5!) So I ended up with 4 unsmelted chaosium and 1 useless lorium.
It is a small thing, but especially with the cost increasing with each turn, it is very frustrating that it seems to pick the ores that I really don't want to waste my stoke turns on.