A very fine grained rock formed in ancient ocean sediments. It often has a semi-glassy finish and is usually white, pinkish, brown, gray, or blue-gray in color. It can be shaped into arrowheads by chipping. It has often been called flint, but true flint is found in chalk deposits and is a distinctive blackish color.
click here...
Sexual Intercour...
Cherenkov Detector
Chert
