# Coal rock

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Release date 4 January 2001 (Update) No No 30 50 Coal (255 coins) 1 Varies This rock contains coal.

A Coal rock is a rock that contains coal. Players with a Mining level of 30 can mine coal rocks with a pickaxe, granting 50 Mining experience. Coal rocks can be found in numerous mines throughout RuneScape, most abundantly in the Mining Guild.

On rare occasions the rock may give an uncut sapphire, emerald, ruby or diamond.

Coal is used in combination with ores such as iron, mithril, adamantite and runite to smelt bars in a furnace to create armour and weapons with Smithing.

One of the best ways to mine coal is to use skills necklace teleport to mining guild, and bank using either the TokKul-Zo or the Ring Of Duelling. Having a coal bag from dungeoneering rewards will hold 30 coal for you making your trips longer.

## Respawn rateEdit

Coal, like all other mined rocks, respawns at a rate indirectly proportional to the number of people in the rock's RuneScape world. If the world is empty, the ore respawns in 1 minute; if it is full (with 2000 players), it respawns in 30 seconds. Thus the respawn rate of coal is

$60-\frac{3x}{200}$ seconds,

where x is the number of players in the world.

A table of respawn rates is given below.

Players 0 200 400 600 800 1000 1200 1400 1600 1800 2000
Respawn time 1:00 0:57 0:54 0:51 0:48 0:45 0:42 0:39 0:36 0:33 0:30