Red Flint Sand and Gravel, it should be available nation wide at sand blastring/filter sand suppliers. You can save a ton of cash buying gravel this way and it is super high quality.
I bought a 100 pound bag of 1/16 to 1/8th gravel for 10 bucks, I also bought some .80 to 1.20 mm for 10 dollars per 100 pounds, I have the smaller .80/1.20mm in my tank now and it is just incredible, very rounded edges and the fish love it, and you can still vacuum it because it is not as fine as sand, but fine enough for plants, cichlids etc.
Check it out here:
I sent them a email asking them where the closest distributor was to my city(I live in Milwaukee) and it turned out it was 5 minutes from my workplace.
I can post some pictures of the both sizes I have if you like. Just let me know.