Beach pebbles/rocks

[hillegom]

As said you do not want the minerals in the rock to leach out so pick rocks carefully.
Rocks will explode if heated too fast in the air ( as when you throw them in a fire.)
Thats because the water in the rock turns to steam and cannot escape fast enough.
Boiling rock in water is ok because the temp will never rise higher than 100 deg C
So no steam as long as the rocks are submerged

[strezman]

Thanks for the responses.. Hmm, this seems to be a silly question. But what do I look for in a safe rock then? Non porous??

[reeferfulton]

i used dozens of granite looking rocks off the beach to place frags on .. I just hand washed with vinegar and water. IMO granite type beach rocks once cleaned wont / cant leach anything.. and make for nice zoo colony rocks.. Its is easier to frag zoos and palys off a smooth granite rock then say a porous reef rock

[WarDog]

Igneous plutonic FTW.

[strezman]

This is turning into a science class really fast lol. Probably the most vague description but, any idea about smooth blueish very solid seeming rocks?? I'm sure a pic would be easier but I can't make it to the beach today

[Coasting]

Elementary school science!!!!
Drip some vinegar on it, does it fizz?


http://www.minsocam.org/msa/collecto...d/rock_key.htm

Most of the rocks we find around here in riverbeds are a pretty safe bet

[GoFish]

What are you planning on using these rocks for btw? Been there done that with beach rocks. Are you wanting more biological filtration? Or wanna use them as a substrate in your display?

[WarDog]

Blueish and smooth is probably sedimentary. Not an ideal choice. Neither is metamorphic, can contain metals. Best bet is rock forged from 'liquid hot magma' (Dr.Evil voice), which is Igneous.