Flint, also called chert, is made up of densely packed finely grained quartz. Flint is classified as a cryptocrystalline, which means that the crystalline structures are so fine that they are not even distinguishable under a microscope. Flint’s color varies from grey to black, being nearly opaque. On a chemical level, flint is not as pure as quartz -- the impurities can account for the material’s opaqueness.

Black Flint in New Jersey

New Jersey is one of about twenty states that flint can be found in the wild. No digging is needed in finding flint naturally, one only needs to walk along a gravel road or along a creek or waterbed to find flint. In much earlier times, flint was one of the primary materials used in making projectile points and knives!

• The material is hard, yet has a tendency to split into multiple pieces.

• Flint is homogenous and has a smooth, non-grainy surface, unlike most rocks.

• The material is tough and less brittle than other types of quartz.

• Despite the material being homogenous, stress dissipates throughout the material. This means that stress on the rock will not spread and crack through the entire rock. This is due to the fact that black flint is not crystalline.