It has a 2nd flower now....
Brett, sorry, I do not know what its in, I bought it relatively recently so I have not repotted it yet. But is looks as if at least a part of it is sponge-rock-could be DE as well. Do not know too much about the culture requirements, but learnt to know that if temperatures are too low, the leaves attains a bronze hue. After moving to warmer conditions the bronzing stopped and relatively soon after, the bud appeared. So blooming might be triggerered by a cold spell. Might be something to check for those that are incapable of blooming it.
B