No I have a few agates. Some from T/C and they were no better then a good Thomas Fuller Black English Flint for ignition numbers. I have a Lyman Agate on my GPH and it is still setting the rifle off. But I only have maybe 40 rounds through it.
I purchased a hundred or so Black English Flints one time when they were on sale. Then I sat down with a diamond wheel and de-humped all of them. So i have a lot of flints to shoot off.