In geology and geomorphology, the term "patina" is used to refer to discolored film or thin outer layer produced either on or within the surface of a rock or other material by either the development of a weathering rind within the surface of a rock, the formation of desert varnish on the surface of a rock, or combination of both.It also refers to development as the result of weathering of a case-hardened layer, called "cortex" by geologists, within the surface of either a flint or chert nodule.Garden furniture is listed in the Garden Furnishings category.Related items may be found in the Architectural, Brass, and Store categories.The chemical process by which a patina forms or is deliberately induced is called patination, and a work of art coated by a patina is said to be patinated.The green patina that forms naturally on copper and bronze, sometimes called verdigris, usually consists of varying mixtures of copper chlorides, sulfides, sulfates and carbonates, depending upon environmental conditions such as sulfur-containing acid rain.
and wooden furniture (sheen produced by age, wear, and polishing), or any similar acquired change of a surface through age and exposure.
A patina layer takes many years to develop under natural weathering.
Buildings in damp coastal/marine environments will develop patina layers faster than ones in dry inland areas.
Facade cladding (copper cladding; copper wall cladding) with alloys of copper, e.g.
brass or bronze, will weather differently from "pure" copper cladding.