I happened to find this volcanic black sand, which is presumably composed of black quartz/silica glass.
http://www.specialistaggregates.com/san ... p-214.html
http://www.specialistaggregates.com/san ... p-215.html
They however don't seem to have a medium grade of that, which is what I'd ideally have been looking for.
It's not as cheap as Black Diamond, which is actually what I had been first trying to find. Black Diamond or Black Beauty is cheap, but not quite as cheap if you had to ship it from the states...
NOTE: I reread the description and it turns out this sand may be painted instead of being naturally black quartz. It says fish-safe, but always good to investigate that cautiously!
http://www.specialistaggregates.com/san ... p-214.html
http://www.specialistaggregates.com/san ... p-215.html
They however don't seem to have a medium grade of that, which is what I'd ideally have been looking for.
It's not as cheap as Black Diamond, which is actually what I had been first trying to find. Black Diamond or Black Beauty is cheap, but not quite as cheap if you had to ship it from the states...
NOTE: I reread the description and it turns out this sand may be painted instead of being naturally black quartz. It says fish-safe, but always good to investigate that cautiously!