Ore deposits are placed by the world generator. An offline copy of the placement code was run over 283 generated deposits from six seeds, and 281 of them floated, by up to 46 cm, because an upright rock on a slope lifts off on its downhill side.
The obvious fix, standing rocks upright and burying them deeper, sank the uphill side by up to 94 cm and put some rocks out of reach of a pickaxe. The final rule tilts a rock onto the slope by up to 30 degrees and buries it by one centimeter. None float, the deepest contact is 24 cm, and a rock can be reached from seven of eight directions on average.
The reach test was strict enough to matter twice. A 6 cm burial missed it by 1.14 cm and was reverted. Each deposit also received its own rotation, size and rock type, and a size range starting at 0.9 left one rock 1.6 cm out of reach, so the range starts at 1.0. These results cover six seeds in an offline copy of the code, not every possible world.
