Named for French geologist Déodat de Dolomieu, Dolomite is a limestone-like rock that is abundant in the geological record prior to 66 million years ago, appearing less often in later formations.

The issue of this "Dolomite Problem" has puzzled geologists, with one theory being that Dolomite forms due to microbial colonies that were more common during the early years of Earth's history.

This specimen is a piece of Duck Creek Dolomite from the Ashburton Basin in Western Australia. It dates to the Proterozoic Eon 1.8 billion years ago and shows stromatolite evidence of Pilbaria perplexa, a microbe that may have aided in the Dolomite's formation.

The specimens ships in a sturdy carton and comes complete with a certificate of authencity. Check out all of our available Dolomite specimens in the collection below!

Dolomite is a sedimentary rock similar in appearance and texture to calcium-carbonate-based limestone but with the inclusion of magnesium. In addition to the presence of magnesium, Dolomite rock can be differentiated from limestone from the presence of the mineral dolomite, which can form large clear crystals. Dolomite also shows a greater resistance to acid than limestone but is still quick to erode when it comes into contact with water.

Just how magnesium appeared in these rock formations is somewhat mysterious, but it is believed that magnesium-producing microbial mats precipitated the formation of the rock. This could account for the “Dolomite Problem”: the question of why Dolomite is abundant in ancient rock formations but scarce in newer geological deposits, and the difficulty of precipitating Dolomite in a laboratory environment.

Dolomite’s interactions with microbes means that deposits of the rock often preserve ancient forms of microbial life. In Western Australia’s Ashburton Basin, the Duck Creek Dolomite deposits show evidence of Pilbaria microbes dating to the Proterozoic, 1.8 billion years ago. 

Pilbaria is a cyanobacteria that forms stromatolites which are laminated mats of sediment produced by microbial life. Duck Creek Dolomite specimens show firsthand that the domain of geology and the processes of life were closely intertwined in the early years of our planet’s history.