Ice Slopes do not melt currently (as of R29 in February 2016) in hot biomes, not even on the Lava layer. So they can be used to make rinks and "Ice railways" to slide all over any Creativerse world powered by Fans. Ice can be found in frozen Ocean biomes and frozen rivers, often hidden underneath a short ("stompable") layer of Snow, but sometimes also in the form of cataracts of frozen water. Just like Ice, Ice Slopes also require at least a Stone Mining Cell to be equipped to collect them from the world.