Sarngaran (Sindarin: Red Stone) is a red stone that covers much of the surface of, and found exclusively in, the Red Mountains, giving them their name. It may also be found in random underground deposits in this biome.
Sarngaran can be seen as a counterpart to the Sarlluin stone, found only in the Blue Mountains. It was never mentioned by Tolkien how the Red Mountains looked and so it would be logical for this mountain range to be red-coloured in the mod. Theoretically, the Red Mountains could have been red due to massive lodes of iron, but Sarngaran will be useful when the Red Dwarves are added.