I would imagine that the 9% calcium would benefit the pings, I should also clarify, I smash it in a bag with a hammer, but only the ultra aerated stuff from west of here, if I get the basalt from north of here (solid black basalt) it is much harder and sends shards, makes dust not gravel and the bag is ruined at the end, so do not try crushing it unless you have a crusher.
Drosera Spathulata, adelae and several utrics and pings I have love Basalt.
I use large 1inch gravel for some of the nep pots and the pings, but the utrics (longifolia and livida) and the drosera like small 1cm gravel.
I have also tried sand, granite gravel and pumice with my pings, but basalt seems best, pumice would be but the shops here sell pumice collected from a beach, its fine for orchids but kills carns unless washed.