Silcrete

Silcrete can be found at a lesser extent throughout the world especially England (e.g. Hertfordshire puddingstone and sarsen stone), and France.

[1] In the Great Plains of the United States, polished silcrete cobbles are locally common on the surface and in river gravels east of the outcrops of the Ogallala Formation.

It is widely believed by stone tool experts that the technology to treat silcrete by burying under a hot fire was known 25,000 years ago in Europe.

[5][6]In South Africa at Pinnacle Point researchers have determined that two types of silcrete tools were developed between 60,000 and 80,000 years ago and used the heat treatment technique.

[4][7] The peoples of the African Middle Stone Age (MSA) showed a preference for silcrete tools, sourcing the material from up to 200 km to use in place of more accessible quartz and quartzite.