Magadiite

Magadiite is a hydrous sodium silicate mineral (NaSi7O13(OH)3·4(H2O)) which precipitates from alkali brines phase. It forms as soft (Mohs hardness crystal masses. The mineral is unstable and decomposes during diagenesis leaving a distinctive variety of chert

The mineral was first described by Hans P. Eugster in 1967 for an occurrence in Lake Magadi , and is also found at Olduvai Gorge It is also reported from alkalic intrusive as in Mont Saint-Hilaire