Iridescence in the context of "Bismuth"

An optical disc is a flat, usually disc-shaped object that stores information in the form of physical variations on its surface that can be read with the aid of a beam of light. Optical discs can be reflective, where the light source and detector are on the same side of the disc, or transmissive, where light shines through the disc to be detected on the other side. They may contain analog or digital information, or a mixture of the two. Their main uses are the distribution of media and data, and long-term archival storage.
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A biological pigment, also known simply as a pigment or biochrome, is a substance produced by living organisms that have a color resulting from selective color absorption. Biological pigments include plant pigments and flower pigments. Many biological structures, such as skin, eyes, feathers, fur and hair contain pigments such as melanin in specialized cells called chromatophores. In some species, pigments accrue over very long periods during an individual's lifespan.

Pigment color differs from structural color in that it is the same for all viewing angles, whereas structural color is the result of selective reflection or iridescence, usually because of multilayer structures. For example, butterfly wings typically contain structural color, although many butterflies have cells that contain pigment as well.

The meat ant (Iridomyrmex purpureus), also known as the gravel ant or southern meat ant, is a species of ant endemic to Australia. A member of the genus Iridomyrmex in the subfamily Dolichoderinae, it was described by British entomologist Frederick Smith in 1858. The meat ant is associated with many common names due to its appearance, nest-building behaviour and abundance, of which its specific name, purpureus, refers to its coloured appearance. It is among the best-known species of ant found throughout Australia; it occurs in almost all states and territories except for Tasmania. Its enormous distribution, aggression and ecological importance have made this ant a dominant species.

The meat ant is monomorphic (occurs in a particular form), although there is evidence that certain populations can be polymorphic. It is characterised by its dark-bluish body and red head. It is a medium to large species, measuring 6–12 mm (0.24–0.47 in). The workers and males are approximately the same sizes at 6–7 mm (0.24–0.28 in) and 8 mm (0.31 in), respectively. The queens are the largest and appear mostly black, measuring 12.7 mm (0.50 in). The iridescence in workers ranges from green or blue to plain green and purple, varying in different body parts and castes. Meat ants inhabit open and warm areas in large, oval-shaped mounds that are accompanied by many entrance holes. The nest area is always cleared of vegetation and covered with materials including gravel, pebbles and dead vegetation. They are also polydomous, where a colony may be established in a series of satellite nests connected by well-defined paths and trails. Satellite nests are constructed away from the main nest and nearby areas with valuable food sources so workers can exploit them.

Nacre (/ˈneɪkər/ NAY-kər, also /ˈnækrə/ NAK-rə), also known as mother-of-pearl, is an organic–inorganic composite material produced by some molluscs as an inner shell layer. It is also the material of which pearls are composed. It is strong, resilient, and iridescent.

Nacre is found in some of the most ancient lineages of bivalves, gastropods, and cephalopods. However, the inner layer in the great majority of mollusc shells is porcellaneous, not nacreous, and this usually results in a non-iridescent shine, or more rarely in non-nacreous iridescence such as flame structure as is found in conch pearls.

Lustreware or lusterware (the respective spellings for British English and American English) is a type of pottery or porcelain with a metallic glaze that gives the effect of iridescence. It is produced by metallic oxides in an overglaze finish, which is given a second firing at a lower temperature in a "muffle kiln", or a reduction kiln, excluding oxygen.

The technique of lustreware on pottery was first developed in Mesopotamia (modern Iraq) in the early 9th century. Initially mostly decorated with geometric patterns, by the 10th century an Iraqi style with the design dominated by one or two large figures developed. After the Fatimid conquest of Egypt in 969, it became a great centre of lustreware production until the Fatimid Caliphate fell in 1171, soon after the potter's quarter of the capital Fustat (Cairo) was burned in 1169. It is thought that the Fustat potters dispersed to both Syria and Persia, and lustreware appears there about this time; later the devastating conquests of the Mongols and Timur disrupted these industries. The technique had spread to al-Andalus (the Islamic Iberian Peninsula). Hispano-Moresque ware in lustre was mostly produced in Christian Spain, especially in the region of Valencia – in particular Manises – and later Barcelona.

Structural coloration in animals, and a few plants, is the production of colour by microscopically structured surfaces fine enough to interfere with visible light instead of pigments, although some structural coloration occurs in combination with pigments. For example, peacock tail feathers are pigmented brown, but their microscopic structure makes them also reflect blue, turquoise, and green light, and they are often iridescent.

Structural coloration was first described by English scientists Robert Hooke and Isaac Newton, and its principle—wave interference—explained by Thomas Young a century later. Young described iridescence as the result of interference between reflections from two or more surfaces of thin films, combined with refraction as light enters and leaves such films. The geometry then determines that at certain angles, the light reflected from both surfaces interferes constructively, while at other angles, the light interferes destructively. Different colours therefore appear at different angles.

Chromatophores are cells that produce color, of which many types are pigment-containing cells, or groups of cells, found in a wide range of animals including amphibians, fish, reptiles, crustaceans and cephalopods. Mammals and birds, in contrast, have a class of cells called melanocytes for coloration.

Chromatophores are largely responsible for generating skin and eye colour in ectothermic animals and are generated in the neural crest during embryonic development. Mature chromatophores are grouped into subclasses based on their colour under white light: xanthophores (yellow), erythrophores (red), iridophores (reflective / iridescent), leucophores (white), melanophores (black/brown), and cyanophores (blue). While most chromatophores contain pigments that absorb specific wavelengths of light, the color of leucophores and iridophores is produced by their respective scattering and optical interference properties.