What Kind Of Rock Goes With Black Gravel?

Hello all,

I'm re-scaping my aquarium from brown gravel to finer black gravel. I would like to create a small cave for my loaches and ottos. I would also like to add plants to the top of the cave so it's not totally bare. Can anyone suggest a color or type of rock that pairs well with black gravel and plants?

 

river rock, seiryu stone, slate

 

Granite but I don't know if it affects pH? I have one piece in my 55 and haven't noticed anything but it's only one piece.

 

I'd go with a black slate or black seiryu. Black lava rock is a cheaper alternative. To be fair, any dark grey or black colored stone should look decent.

 

honestly black goes with everything, so no matter what colour stone you choose, it'll still look great! I have dragon stone, multi-coloured river rock, and seiryu stone in my black sand tanks.