Perlite is not a sub. For granite. It more resembles turface or floor dry, as it retains some water. I too had a tough time finding crushed granite, as the feed stores near me only carried oyster shell. You can use coarse builders sand, or pool filter sand. Size should be around 1/8th inch. I have been using a mixture of coarse sand and screened pea gravel from walmart.

I actually used the gritty mix to root cuttings. I had 3 cuttings that I had acquired that had root initials. I stuck them in 20oz cups with the mix, put a ziplock bag over for humidity. 3 weeks later, strong roots are showing, and leaves are developing nicely.

I see. Like I said, I found granit but Im not willing to pay a dollar a pound. The pool sand here is more like beach sand, 1/64". Ill keep looking.

At the feed store ask for " Cherry Stone "
it replaces the granite in the mixture. Its used for chickens to help them digest.
This is what i was told here on forum if granite was difficult to fine or too expensive by Tapla.

Bill, you can also call a local masonry supply store. They have all sorts of grades of sand. Make sure it is silica.