👉 "Millerite," also known as mullite, is a naturally occurring mineral that occurs in the Earth's crust and mantle. It is composed of iron oxide (MnO2) and aluminum oxides, which are found in the form of small crystals or grains. The mineral is known for its unique properties such as high electrical conductivity, low thermal expansion, and high density. The term "millerite" was coined by a chemist named William Henry Miller in 18
