Grimes Graves

Grime's Graves is a large Neolithic flint mining complex near Brandon in England close to the border between Norfolk and Suffolk. It was worked between circa 3000 BC and circa 1900 BC, although production may have continued well into the Bronze and Iron Ages (and later) owing to the low cost of flint compared with metals. Flint was much in demand for making polished stone axes in the Neolithic period. Much later, when flint had been replaced by metal tools, flint nodules were in demand for other uses, such as for building and as strikers for muskets.

• http://en.wikipedia.org/wiki/Grimes Graves