tinman

Has anyone ever checked a quarry for rocks that mite contain minerals that would be good for plant growth? i know many people buy inert gravel there for their tanks but i was just wondering if any of them would be similar to onyx sand or something along those lines. i know it mite sound like a silly question or else everyone wouldn't be wasting their money on the more expensive commercial substrates but i felt a need to ask it anyway.

thanx heaps
Tin

pineapple

Hammering rocks into sand sized particles is usually reserved for prisoners, is it not?

But, in my experience, blue metal, a sort of basalt which is used for roads and comes in various sizes can be quite good in finer sizes. The colour is also suitable in that it tends to be dark black sometimes slightly blue-black. Basaltic or basic rocks tend to be ricker in iron and low in free silicates (such as quartz).

Andrew Cribb