It's far more popular than it once was... but like I said, I took years to track down an affordable option that would work for cories. I started with play sand... which they love by the way... but wouldn't do that again. It was too light in color and took way too long to rinse... I burned out two filter motors because of it getting sucked up into the filter. (My BN pleco likes to rearrange my sand at night...and kicked up a bunch of it)
My new filter is a canister, and this ceramaquartz never clouds up like the play sand. Small enough and soft enough for the cories, but heavy enough to sink well. And if you don't like 'black' they offer about a dozen other colors, I think.