Geyserite, or siliceous sinter, is opaline silica deposited as crusts and layers around hot springs and geysers. Silica enclosing many small cavities makes it porous, and the botryoidal form is called fiorite. It should not be confused with calcareous sinter, which is made of calcium carbonate. In 2017, 3.48-billion-year-old geyserite from the Pilbara Craton of Western Australia was reported as possible evidence of the earliest life on land.
Is this geyserite?
2-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Read the textureLook at a fresh break with a hand lens. Texture: Porous crusts and layers; botryoidal form is called fiorite.
- 2Pick out the mineralsComposition: Opaline silica. Identify the two or three most abundant grains.
All properties
- Uses
- Scientific research
- Host rock
- Crusts and layers around hot springs and geysers
- Texture
- Porous crusts and layers; botryoidal form is called fiorite
- Composition
- Opaline silica
Where rockhounds find geyserite
Classic worldwide localities
- Pilbara Craton, Western Australia (3.48-billion-year-old geyserite)
Field-hunting tip
Where it forms: Crusts and layers around hot springs and geysers.
Common questions
Where is geyserite found?+
Notable localities include Pilbara Craton, Western Australia (3.48-billion-year-old geyserite).
What kind of rock does geyserite form in?+
Where it forms: Crusts and layers around hot springs and geysers. Working float back to the host body is the standard way to chase a fresh occurrence.
What is geyserite used for?+
Geyserite is used in scientific research.
Find geyserite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
