Geyserite

{{Short description|Form of opaline silica often found around hot springs and geysers}}

Image:Geyserite.jpg]]

Geyserite, or siliceous sinter, is a form of opaline silica that is often found as crusts or layers around hot springs and geysers. Botryoidal geyserite is known as fiorite. Geyserite is porous due to the silica enclosing many small cavities.{{Cite web|url=https://www.britannica.com/science/sinter|title = Sinter | mineral}} Siliceous sinter should not be confused with calcareous sinter, which is made of calcium carbonate.

In May 2017, evidence of the earliest known life on land may have been found in 3.48-billion-year-old geyserite uncovered in the Pilbara Craton of Western Australia.{{cite news |author=Staff |title=Oldest evidence of life on land found in 3.48-billion-year-old Australian rocks |url=https://phys.org/news/2017-05-oldest-evidence-life-billion-year-old-australian.html |date=9 May 2017 |work=Phys.org |access-date=13 May 2017 }}{{cite journal |last1=Djokic |first1=Tara |last2=Van Kranendonk |first2=Martin J. |last3=Campbell |first3=Kathleen A. |last4=Walter |first4=Malcolm R. |last5=Ward |first5=Colin R. |title=Earliest signs of life on land preserved in ca. 3.5 Ga hot spring deposits |date=9 May 2017 |journal=Nature Communications |volume=8 |pages=15263 |doi=10.1038/ncomms15263 |pmid=28486437 |pmc=5436104 |bibcode=2017NatCo...815263D }}

File:Chinese Spring upper geyser basin yellowstone.jpg, Yellowstone]]

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