Translations:GregTech 5/Mining and Processing/6/en

Ore vein generation takes place as a series of steps. First, at the center of every 3x3 chunk area a random ore mix is chosen. If that ore mix cannot generate within the current dimension, the generator tries again. If the ore vein is allowed, a random height will be chosen within the mix vein's Minimum and Maximum height values, and ore generation will propagate out from that point. However, as ores are placed by replacing Stone, Red/Black Granite, Netherrack, or End Stone, if the generation area contains none of those materials ore blocks will not generate. As such, it is possible to encounter areas that do not contain mix veins. In Forests, Plains, and similar biomes, this happens about a quarter of the time. In mountains or extreme hills, it happens fairly rarely, while deep oceans often will not have Mix Veins below them.