How can I remove a black mark from wood furniture top?

Awe that's too bad!! you may need to use a thick stain that covers almost like paint. Good luck!

Not knowing what the black mark is it probably soaked into the grain. Use a Q tip and dip it in some bleach. Rub it on a small area of the 'X', let it sit for a while and see if it lightens the black. If it does then you can do the whole "X".

How about trying a deep mahogany stain?

If it was under the veneer it probably has penetrated the wood grain. amything that takes it up will probably cause any stain to be different in that spot. I think you will need to use a very dark stain to cover it up.

Have you tried Comet powder ? My children , when they were little , each got creative on different surfaces with Sharpie markers. Always black ones, since that's what I used at work and they traveled back and forth in my pockets . Comet never failed to rescue my home's furniture , walls, you name it .

Goo Gone to the rescue. If thats a black marker, Goo Gone will lift it, BUT you must try several times. Denatured alcohol can be used too but you may not get the same results. Good luck!