reef rock from Hawaii

[grochmal]

I'm on vacation in Hawaii right now and found this part of the beach down from where I'm staying that has a man-made inlet with a bunch of coral rubble on it.
It's being used as gravel, basically.

Question is, would it be safe to put into my tank after maybe bleaching and curing it?
Here is a sample piece.

 

[nemofish2217]

looks kind of dense....not much porus room for good bugs? that would reduce your biodiversity and biofiltration...would this rock just be a 'centerpiece' or would the majority of your reef be made of this stuff? I guess you would need to know what this stuff was made of in order to know if you could put it in your tank....

 

[grochmal]

It looks to me to be just dead coral skeletons, meaning calcium carbonate.
I would just be using the rocks as additional live rock, not for visual display.
It is definately dense though.