I totally agree but will go a little deeper from lapidary experience in my past. Your lava rock is VERY porous and will, by nature, attract minerals. These minerals will cause crystal formations which is probably what you are seeing.It's part of the rock. Nothing to worry about. Sort of like knots in wood.
-------------------------------------------------
HAVE YOU VOTED FOR TANK OF THE MONTH YET
The color of lava is dependent on its chemistry and how long it is exposed to oxygen while staying molten. As a result it can be white, red shades of gray or black.@jaylach @Lynnzer is it normal for lava rock to turn black after being in aquarium for awhile? does that mean anything
Drip some vinegar onto the white material. It it fizzes it is probably calcium carbonate which could affect GH and KH and PH.just wondering if this stuff attached on my lava rock is safe for fish. I’m pretty sure its just quarts and a tiny bit of crystals