Aluminium in octahedral sheet of clay mineral indicates

Aluminum is an octahedral sheet of clay mineral that indicates Dioctahedral.
Octahedral sheets of clay are composed of individual octahedrons that share edges composed of oxygen of hydroxyl anion groups with Aluminium, Magnesium and Iron typically serving as the coordinating cations.
An aluminum octahedral sheet of clay has six OH ions at each of the six corners of an octahedron, with the aluminum atom at the center of the octahedron.