found some bigger stuff, Dunno if you want to try bigger, but not cheap
https://www.bcsands.com.au/index.php?ma ... pmcpgojn3120-30mm $31/15kg bag, but its the black stuff and very rounded.. talked to the suppliers up here in brissy (this stuff must be imported), they know sfa other than its lava rock and not artificially coloured. You might find a closer stockist here
http://kashmiripebbles.com.au/stockists/