casa Montero
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Flint is a sedimentary rock made of SiO2. In some cases it is formed by the accumulation and compression of siliceous organisms (organic flint), and on others it appears because of the attack of siliceous solutions on already present rocks and sediments (silicification). During such attacks, the initial minerals of the rock or sediment are dissolved out, and silicon minerals precipitated in their place (usually quartz and opal); this gives rise to inorganic flint. Flint is very hard, and perfect for the manufacture of tools by knapping. Its fracturing is predictable, aiding in the making of different types of tool. It was one of the most commonly used resources of prehistoric times.

The flint layers exploited at Casa Montero were produced by the silicification of magnesian clays. As the clays were replaced, part of the opal initial formed underwent aging, leading to its recrystallization and the formation of quartz. As a result, lenticular layers and nodules of flint and with high exterior contents of opal but with micro-cryptocrystalline quartz interiors appeared in the clay. This high quality flint was perfect for knapping.

A flint nodule from Casa Montero
Photo: The Casa Montero Team
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