If its for fire making, argillite is a passable alternative.. not quite as sharp or "glassy" but it makes adequate sparks for char cloth. As far as flit knapping goes, im not sure. i know it was used by Maori for tool making..
hope this helps.
Hi Ross thanks for the reply. Yes it's for fire lighting, do you know if you can find argillite anywhere south of Canterbury as I live in Otago.
And thanks for your help,
Cheers to you Ross