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Shining a light on the Unsung Heroes of SA’s natural history

Mechanical preparation of fossils

DITSONG National Museum of Natural History unsung heroes curators
Lystrosaurus
DITSONG National Museum of Natural History unsung heroes curators
Diictodon

When fossils are found in the field, they are usually encased in rock called ‘the matrix’. This often comprises mudstone or siltstone. In order to study and fully describe the fossil, it must be prepared out of the matrix. For this mechanical preparation, an air scribe with a tungsten tip is needed. This tool is similar to the tool used by dentists and engravers. For protection against dust, the preparators wear protective eyewear (Optivisor), a dust coat, mask, and often earplugs. The dust coming off the fossil may contain radon, which is harmful to the lungs of the person inhaling it and can cause cancer. The fossil is not fully freed from the matrix, but remains in a sandwich of matrix to keep it together. It takes practice to master the skill required to use the engraver to carefully remove the matrix by scraping thin lines into it. The whole process of uncovering a fossil can take up to three years.

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