Silcrete is an indurated soil duricrust formed when silica is dissolved and resolidifies as a cement. It is a hard and resistant material, and though different in origin and nature, appears similar to quartzite. It is common in the arid regions of Australia, often forming the resistant cap rock on features like breakaways.
In Australia, silcrete was widely used by Aboriginal people for stone tool manufacture, and as such, it was a tradeable commodity, and silcrete tools can be found in areas that have no silcrete groundmass at all, similar to the European use of flint. Tools made out of silcrete are difficult to make with flintknapping techniques. This has led some researchers to conclude that silcrete may have been heated to aid with creating proper flakes prior to knapping. This process may have been the first use of so called pyrotechnology by early mankind. [1]
In Africa, researchers have determined that two types of silcrete tools were developed between 60,000 and 80,000 years ago.[1]