Actually Chert is an interesting subject - lots of unknowns about it. Rick Behl from CSULB studies it a bit. Another 2 women I know have done a lot of research/investigations on it in the Monterey formation. The silica comes from plankton like ocean critters.

Here in California it is found to be a reservoir rock in places like Santa Barbara - normally you wouldn't find oil in Chert (more likely to find it in sandstone).

Rick has an article off his page on the formation of chert.

It is also a rock with Conchoidal fracture much like flint and obsidian so it was widely used for such things as arrows and spears and other rock tools. It comes in all sorts of colors depending on other impurities or minerals around it.

Canie

• Rick Behl