|Release||17 September 2009 (Update)|
|Location||Living Rock Caverns|
|Ore||Coal (177 coins)|
|Max yield||Until despawns|
|A large concentration of coal.|
Concentrated coal rocks are located in the Living Rock Caverns beneath the Dwarven Mines. 50 experience is given for each ore mined. There are eight of these rocks in the Caverns, and they require 77 Mining to use. Concentrated coal rocks contain a much larger supply of coal than a normal coal rock, with a chance at receiving two ores at once, until they collapse. The double ore bonus stacks with the bonuses from Varrock armour and the reward from the Shooting Star Distraction and Diversion, potentially resulting in a bonus of four ore at once. Gems cannot be obtained from this type of rock. A Coal Bag, which can hold 81 coal, will allow the player to store coal.
After a random time interval a concentrated coal rock will collapse and cannot be mined from until it replenishes itself, which is also random. Therefore no competition exists for resources when mining from concentrated coal rocks.
The rocks are guarded by the creatures of the Living Rock Caverns in the form of living rock protectors, living rock strikers, and the living rock patriarch. These monsters are aggressive and pose a threat to any players mining from the concentrated rocks, so it is generally advised to mine on world 84, the official world for the Living Rock Caverns. Multitudes of players mine and fish in the Living Rock Caverns on this world, lessening an individual player's chance of coming under attack. However the extremely high volume of players on this world makes lag an ever-present threat.