Live rock question

[MikeP]

I've been building up the supply of LR in my tank. Being new to this I have been checking out different stores in town, I was wondering if it's o.k. to mix types of LR? All the rock I have bought looks the same so far but the latest store I was in has FUJI LR and it seemed to have a different look. The FUJI LR was a bit more expensive ($7.99/pound) but the guy at the store claims it is lighter the the stuff I bought elsewhere.

Thanks for any help
M