Flint. A massive, somewhat impure variety of quartz, in color usually of a gray to brown or nearly black, breaking with a conchoidal fracture and sharp edge.
“Let us urge forward our spirits, and make them approach the invisible world, and fix our mind upon immaterial things, till we clearly perceive that these are no dreams; nay, that all things are dreams and shadows besides them.”
–Henry Scougal, The Life of God in the Soul of Man