Bridgmanite

The Bridgmanite is Magnesium silicate or Calcium silicate mineral. It is the most abundant mineral on the earth. It makes up 70% of lower mantle. It is also called Silicate perovskite. Any material that has crystal structure similar to perovskite is generally categorised as Perovskite mineral. These minerals were first discovered in the Ural Mountains in 1962.

Structure

The perovskite structure or the Bridgmanite structure usually occurs in ABX₃. Here A is the metal that forms cations. It can be magnesium or Calcium. B is another metal that forms smaller cations. They can be silicon or aluminium. And X is oxygen.

Nomenclature

The natural Bridgmanite was first found in Tenham meteorite that fell in 1879 in Australia. However, the name Bridgmanite was given to the mineral only in 2014. Till then it was a perovskite mineral. The name was approved by the International Mineralogical Association (IMA). The IMA is a group of 40 countries. Its main aim is to standardise nomenclature of minerals known to humans. The mineral was named Bridgmanite to honour the physicist, Percy Bridgman. He won the Nobel Prize in Physics in 1946.

How is Bridgmanite formed in the earth’s mantle?

In the earth’s mantle, the Bridgmanite is formed from the decomposition of ringwoodite. The transition of ringwoodite to bridgmanite marks the bottom of mantle transition zone. This zone is located at a depth of 410 to 660 kilometres. The Bridgmanite is not stable in the earth mantle.

Bridgmanite in India

On May 22, 2012, meteor showers occurred in Nagpur. The largest meteorite from the showers weighed one kilogram. When the meteors fall on the earth surface, they are called meteorites. After the meteor shower, scientists collected thirty meteorites. These meteorites were names Katol meteorites. In October 2021, the scientists published certain results based on their research on the Katol meteorites. They decoded how bridgmanite crystallised during the final stages of earth formation. Their findings are as follows:

• The Bridgmanite mineral was formed at a pressure of 23 to 25 Gigapascals
• The previous samples of Bridgmanite found in Tenham and Suizhou meteorites were different from those found on the earth. However, the Bridgmanite found in Katol meteorite closely matched the Bridgmanites synthesized in laboratories.