A Mature juniper tree requires level 42 Woodcutting to chop down, each tree yielding one or more juniper logs, and each log gives 35 Woodcutting experience. They can only be found in the Hosidius House in the city of Great Kourend.
A player may not use a tinderbox on juniper logs to burn them; rather they should be transported to the charcoal furnaces, found just south of the trees.
When a player attempts to use a tinderbox on juniper logs, they will receive the message stating, "The log won't burn properly like that. It might become good charcoal in a suitable furnace."
On the southern shore, a player may pay Smoggy 600 coins in order to tend one of two charcoal furnaces while they incinerate any amount of juniper logs. When this process has finished, a player will obtain juniper charcoal. This process seems to take a significant amount of time and should not be "watched", as with the common error of watching plants grow. The incineration process is a segue into blast mining for the Lovakengj house.
Initial calculations suggest that a juniper log may take as long as 12+ hours to convert into charcoal. Charcoal may not be collected until the process has completed; moreover a player may add as many as 60 juniper logs to either of or both furnace(s).
The process may be slow but each log gives 50 charcoal. Hence filling both the furnaces gives 6000 juniper charcoals.