Lava Rock As A Substrate Micro Mineral Layer

[FishFancier]

Since lava rock found at Lowe's is red, I wondered if it might contain iron and might be a source of micro minerals in a layer of my substrate. Google found that lava rock has a composition that contains numerous minerals. My experience with a good plant substrate is zero. I wonder if a 1/4 inch layer of lava rock covered with mini-pea gravel might supplement or replace Flourite?

 

[Liam]

As far as I know it is inert, i.e. it wont disolve any minerals into the water, so it wouldnt release iron or other nutrients for plant use.