Use the old engineer motto, K.I.S.S... Keep it simple, stupid!
Hopefully this image will show up (moved site hosts recently so this is actually an old image cache).
That's essentially my logo. I have two variants I use, that and one with a line through it instead of of a dot. It works well because it's my initials (JF) combined, and doubles for my site (studio flaagan) as the JF also reads well as an SF.
It's simple, gets the point across, and I can even draw it on top of my lunch take-out box so no-one eats my leftovers by accident.
Now, if you like your lava-O, keep it. Again, simple, easy to stamp onto things. Maybe mess around with different styles of it. I will say that until you *said* it was lava-rock, I had a hard time identifying it as that.