Join Date: Jan 2006
Location: Burnaby, BC, Canada
Another Geo here. Just make sure the rock is really basalt. Lots of people call rocks basalts which are not, and sometimes the basalts will have veins of calcite and other soluble minerals in it. If it's really basalt and it's solid, or the other stuff has been leached out, you're golden.
Filstar pimp #59 (shhhh on the Eheim)