Earth rune

Earth Rune is a free-to-play item on the OSRS Grand Exchange in the runes category.

In-game examine text: "One of the 4 basic elemental Runes."

It has a Grand Exchange buy limit of 50,000 every four hours, a high alchemy value of 2 gp, and item ID 557.

View on OSRS Wiki

Earth Rune shows an active flip setup with a margin of +1 gp and 30,091,572 trades over the last 24 hours.

At the buy limit of 50,000 every four hours, max profit per cycle is about 50.0k gp — high margin with healthy liquidity.