Is there a Hall of Fame for flint knapping? If so, I nominate Pete Davis.
Pete is like the Henry Ford of east coast quartzite knapping. It isn't that he invented the methods as much as improved on them and through online forums and hosting knap-ins has been largely responsible for spreading the knowledge. A huge pile of quartzite chips is forming up and down the east coast directly and indirectly from Pete's pioneering work. No doubt, there are others, and all modern quartzite knappers are standing on the shoulders of the early experimentall knappers like Errett Callahan, Jack Cresson et al, who figured out much of what is known on how quartzite works. I say "how quartzite works" because, for the most part, it is its own animal, and requires tools and techniques different than conventional knapping. This is not to say that there isn't quartzite out there that a good raw chert or rhyolite knapper can't handle, but pieces like that along the east coast are rare. I would say the same about the vast majority of the other notoriously hard east coast materials, argillite and pure quartz. It isn't just that they are hard to flake, they also behave differently than chert (etc.) and there is a learning curve associated with them.
Keith