Help identify this stone

[castle]

I bought these from a shop the other day, they’re light but in one rock you can see a nail embedded in it; man made perhaps?

 

[Conort2]

Looks like massive pieces of alfagrog. Is it light?

 

[seedoubleyou]

Looks like something you’d probably see in a marine system to me mate.

 

[castle]

Good news is I plan to use this in a pico reef 👍

Interestingly it’s not as light as alfagrog but maybe it is and I’ve never used such large pieces?

Thanks team

 

[seedoubleyou]

Good news is I plan to use this in a pico reef

Just give it a good bleach and then cure it for a few weeks to be safe.

 

[castle]

@seedoubleyou yeah that’s a good shout, I think I will; bleach at 10% for 2 days then ill let sit and dry, then ill stick in a bucket of warm salty water for a few weeks with a piece of live rock, should do it?

 

[Tim Harrison]

It looks like some sort of limestone. Does it react with acid?

 

[seedoubleyou]

It looks like some sort of limestone. Does it react with acid?

My thoughts exactly, probably mined for the marine trade, to avoid taking from the ocean.

 

[_Maq_]

A slag?

 

[PARAGUAY]

A slag?

To do with coal by products?