Occurs in Pinal County.
Chemical Formula: Mg2Al(AlSiO5)(OH)4
Specific Gravity: 2.9-3.1
Amesite is a phyllosilicate. These are sheet-like silicate minerals. Specifically, amesite is a member of the chlorite group of minerals. It is named after James Ames, an American geologist. Amesite is a relatively rare mineral and is often found in metamorphic rocks, especially those that have undergone low-grade regional metamorphism.
Amesite is characterized by its greenish color and its crystalline structure, which consists of layers of silicate tetrahedra bonded together by octahedral layers of aluminum and magnesium cations. This layered structure gives the mineral its characteristic sheet-like appearance.
One of the noteworthy properties of amesite is its cleavage, which allows it to be easily split into thin, flexible sheets. This property has led to its occasional use in industrial applications as a material for insulating electrical equipment.
Geologically, amesite is associated with the alteration of rocks under low-grade metamorphic conditions, such as those found in contact metamorphic zones around igneous intrusions. It forms as a result of the alteration of minerals like biotite and amphiboles.