|Classification:||Chemical sedimentary rock|
|Location:||Dibona Refuge (46°31'59.78"N 12° 4'27.39"E)|
|Era:||Upper Carnian - Norian (approximately 230 - 210 million years ago)|
|Depositional environment*:||Carbonate substructure (shallow coastal environment)
*) The environment refers to the encasing rock and not to the subject of the photo
The perfectly formed crystals of this rock, just a few hundredths of a millimetre in size, are dolomite crystals. The dark parts that can be seen in the photo are also dolomite, but with much smaller crystals, as small as one thousandth of a millimetre in size. Dolomite is a mineral that is believed to have been formed 250-200 million years ago, when the Dolomite Mountains were formed. The mineral, the rock (dolostone), and the mountains all take their name from Déodat de Dolomieu, the French scientist who first described the rock in 1791. This dolomite is sedimentary, which means that it precipitated from the sea water before the sediment deposited on the seabed. It was formed
in hot and dry environments, similar to the coastlines of the Arabian Peninsula in the Persian Gulf. (24°10’10.00″N 54°7’50.00”E). Today limestone is formed in proximity to sedimentary dolomite. The origin of sedimentary dolomite is a problem that researchers have not yet been able to solve. Even though these rocks are very common, no research laboratory has been able to successfully reproduce the conditions necessary for their formation. Geologists refer to this mystery as “the dolomite problem”. Up until 2012 nobody had ever succeeded in forming dolomite at ambient temperatures, while high temperature dolomite, less common in nature, was successfully synthesized under laboratory conditions already prior to 1850.