What is a geyserite in geology ?

Geyserite : definition

Geyserite is a form of silicon dioxide SiO2 that forms near hot springs and geysers. It is a variety of opal specific to these environments. Traces of the oldest known terrestrial life forms were seen in May 2017 in a 3.48 billion-year-old geyserite discovered in the Pilbara Craton, Western Australia.