The Red Mountains consist of normal stone and a red stone called Caranon beneath a layer of red sand. From this stone, bricks and other building blocks can be made.
At y = 90 and below, grass blocks will generate, with trees such as larch, maple, and spruce. High up in the mountains, snow will generate. Mobs found here (Cows, Boars, etc.) can spawn at higher levels than the grass blocks. When you enter this Biome, you get the achievement "Mountains of the East". This Biome has only one Fast Travel point, introduced in Public Beta 31. The sky in this biome is tinged a pale red colour. The Orocarni follows the new mountain generation style, such as its sister, the Ered Luin.
The Red Mountains Foothills sub-biome surrounds the mountains. They are grassy and contain spruce, oak, maple, and larch trees. Caranon stone spawns underground here in patches, as well as in boulders. This sub-biome has a two variants next to the standard version:
Forest - Forest covered lands.
Light Forest - Lightly forested lands.
Forests may be dominated by one species, creating:
The core of the Red Mountains has no variants, but small patches of the Red Mountains Foothills can occur amidst the mountain ranges. The Red Mountains Foothills are coded as the Mountain variant of the standard Red Mountains biome. That variant has, by default, two dependent variants: Forest and Light Forest.
While currently the Red Mountains only contain the common animals of Middle-Earth, it is likely that they will be the future home of four clans of Dwarves, about which very little was known. A Red Dwarves faction is planned to be added to the mod, encompassing all four of these dwarf clans, along with corresponding structures, equipment, crafting table, et cetera. The four clans were the Stiffbeards, the Ironfists (who lived in the northern parts of the range), the Blacklocks, and the Stonefoots (who lived in the southern parts).
The Red Mountains get their name from the Caranon rock that generates beneath this biome's upper layer of red sand, as well as in underground patches. On its own, this stone is quite useful due to its use in building materials, but the Red Mountains also have the benefit of the most profitable biome in Middle-earth to mine in. The Red Mountains contain all the standard ores, but all of them are twice as common here than in any other biome, while gemstones are three times as prevalent. In addition, this biome is one of only a few biomes where glowstone ore can be found, generating quite frequently up to Y=48.
Ore generation is the same in the foothills as in the Red Mountains themselves, but gemstones are a bit less prevalent.