It’s in essence fine gravel, and some model railway products are the exact same thing but usually more expensive. I do indeed have some that I use as rough terrain scatter or to add some texture and color to rough areas, vacuum it up with a mini-V.
Now, I also tend to use natural sand and dirt a lot. For instance, all of my Vietnam minis are based with red dirt that I scrapped up while travelling through southern Oklahoma. It looks exactly like red laterite, and there are even areas that are so red that it looks like what we think “martian red” should be. My property has 6 different colors of dirt, and I used them all extensively. The little twigs and roots that is sometimes found within also adds to great effect! Why buy expensive stuff when you can have free, organic, free range terrain?
"I saw this in a cartoon once, but I'm pretty sure I can do it..."