I believe Rich is knapping his 'flints' from local chert. Look guys, I have said this many times here: "FLINT" is a common name for the mineral CHERT. Chert is a micro- to cryptocrystalline variety of quartz. So is agate and chalcedony and jasper and a variety of other named varieties. They are all SiO2 (silica) and have a hardness of Mohs=7. Now there can be differences in performance due to impurities, fractures, crystal size, etc. Color, in itself, (typically due to small amounts of impurities)shouldn't matter much. Personally, I see no big difference between french and english flints other than color--certainly not enough to warrant the price differential (which last I bought, french was twice english in cost). Alot of 'cherts' should work in a flintlock, and NDNZ did knap there own flints at times from native chert. Novaculite--a form of chert--also works. Caveat: some forms of chert are "grainier" due to either increased crystal size or porosity, and these will "cut" your frizzen more agressively and shorten its life. Think in terms of the Washita stones versus "hard" Arkansas stones--both Mohs H=7--but the former is coarser textured and cuts faster than the latter, which is used to polish steel. English and french flints are typically very finely textured and that is why they are preferred,
