There are bountiful of options.
- Like what phishy said, power-mining is great and fast. A nice place is lumbridge dungeon. After completing
Death to the Dorgenshun, head back to Zanik's location and you will find a bunch of silver and iron rocks, you can mine on those and drop em -OR- You can sell it to Zanik, because she can give you money for your ore so you can get a little bit of money. (Unless your down there for 2 days nonstop)
- If your looking to make money, there's bounty full of coal at Coal Trucks, located I think northwest of Seer's Village (check your map

). It contains trucks you can load your coal in, but it can carry I think about 108 coal before it gets full. The only problem is that there are level 27 bats located there.
So yeah. Theres plenty more ways, but I usually do this whenever I train my mining.