A lamella is a gill-shaped structure: fine sheets of material held adjacent one another, with fluid in-between-(or simply 'welded'-plates). They appear in biological and engineering contexts, such as filters and heat exchangers. The microscopic structures in bone and nacre are lamellae in the materials science sense of the word.
In chemistry (especially mineralogy and materials science), lamellar structures are fine layers, alternating between different materials. They can be produced by chemical effects (as in eutectic solidification), biological means, or a deliberate process of lamination, such as pattern welding. Lamellae can also describe the layers of atoms in the crystal lattice of a material such as a metal.
In a water-treatment context, Lamellae filters may be referred to as plate filters or tube filters.
This term is used to describe a certain type of Ichthyosis, a congenital skin condition. Lamellar Ichthyosis often presents with a "colloidal" membrane at birth. It is characterized by generalized dark scaling.
The term -lamella- or -lamellae- is also used in the flooring industry to describe the finished top-layer of an engineered wood floor, usually the desired species. E.G. An engineered walnut floor will have several layers of other species of wood and a top walnut lamellae.