Nature & Science
The Alibates flint is more correctly called agatized dolomite, or silicified dolomite. Many archeologists also refer to it as Alibates chert because of its striking colors. The colors in the flint are caused by trace mineral elements within the silica. The most common colors of red, orange and yellow are caused by iron; blues and deep greens are usually caused by manganese.
There are several hypotheses as to how the flint formed within the dolomite. The most widely accepted explanation is that about 670,000 years ago volcanic eruptions occurred in or around what is now called the Yellowstone Country of Wyoming. The resulting silica rich ash drifted above the much older, Permian era dolomite. As rainwater percolated through the ash, the silica dissolved (or went into solution) and soaked into the dolomite. The calcium carbonate which forms dolomite washed out, leaving (as a precipitate) silica dioxide--flint or chert.