Mining yields different materials depending on the rocks you mine, with different rocks belonging to different biomes. However because of spawn behavior rocks (except for gem rocks) can sometimes be found outside their biomes.
Mining Chance Formula:
Note: This information needs to be retested after a recent adjustment patch (March 3rd, 2018).
5% + (Mining Level × Pickaxe Modifier)%
It appears everyone starts with a 5% chance to mine, which increases approximately 1% per level (but still just shy of 100% at level 100 mining). Pickaxes apply a multiplier, lowering the mining cap depending on the type of pickaxe used.
(Different pickaxes require higher character levels to equip, as noted in the second column.)
|Bone Pickaxe||5||?||?||Hasn't been tested.|
|Peddler's Gem||12||Accessory||+6||Also adds +6 chopping.|
|Merchant Cloak||15||Light Armor||+3||Also adds +3 chopping.|
You can also enchant items with a bonus to mining using citrine, quartz, and sapphires.
Different rocks can be better--or even unique--sources for different materials, as detailed below.
Found in the sand biome; prime source for stone, minerals, and precious metals.
Found in the grass biome, a common starter rock that offers little besides stone and flint.
Found in the snow biome, these rocks are a significant source of obsidian.
Mainly found in the Underground, these rocks are very rich in minerals and precious metals.