I would say the triangular piece is a "firestone" and the long one is a pestle...a heavy tool with a rounded end, used for crushing and grinding substances such as spices, grains, herbs etc, usually in a mortar.
The firestone would be use with straight stick and prolly with "bow"... kindling would be set around "divit" in stone... whenglowing emders were achieved they would pick up the stone and dump into a crevice of secondary kindling... hence the shape.
I would dare to say you made a great find.
P.S. Not sure what your laws concerning the matter of artifacts of this nature in your area are but... If legal... go back and see if you can find the "motar"... would prolly look like curved indented stone... maybe 12 to 15 inches .