The price of coal was lowered from $1.00 to $0.40 recently. I asked and was told this was because wood can be converted to coal in a cooking pot. My suggestion is two-fold:

1. Make cooking pots convert wood into charcoal instead of coal.
2. Change the price of coal back to $1.00.

Mining received a collateral damage nerf from this price change, and this is a way to avoid that.