I think what Jim was getting at is that, that is a hardrock cart. Coal, unless an early start-up was quickly mechanized and used larger rail cars, or conveyors to move vast quantities of coal vs. smaller amounts of gold or silver ore. Hardrock mining didn't have the convienience of large rooms as is more typical of coal mining and tends to follow veins that are typically more vertical and are confined to narrow tunnels. Most hardrock mines veins were/are rarely more than a few feet thick (there are exceptions) and the cost of blasting large rooms out of solid rock would be costly, therefore the tunneling was as narrow an as minimal as possible.
AS for contemporary hardrock gold mining, they just remove the mountain, not unlike strip mining. It's much cheaper and low grade ores can be worked economically. If you want to see an example of this form of mining do a search on Cripple Creek & Victor Colorado.
