Hi friends, Newbie here, getting into aquascaping. Hope to get some help on these rocks, for using in my 90 liter aquarium... About fist-size. Fizzes in vinegar (4% acetic acid) and stops after 5-10 minutes. Has little red specks like Rust (might be Iron deposit) and white patches (might be calcium) Has the looks of LAVA rock, but not absolutely sure.. I am extremely tempted to use this in my aquarium. Can I use these, after immersing them in vinegar and boiling water? Help appreciated and thanks in advance.