A harmonised runite rock is a special rock that may appear in the Trahaearn Clan district's mining area in Prifddinas while the Voice of Seren is active for the clan. Only the westernmost rock can become harmonised.
The rocks will collapse after some time, renewing periodically. These rocks may only appear when the Voice of Seren is active, so there will always be an experience boost active when they appear.
Multiple players can mine from these rocks at once and all will receive runite ore as long as it is harmonised. Runite rocks can become harmonised on multiple worlds/servers.
Runite ore rocks cannot harmonise if they are already mined.