Macle is a term used in

crystallography Crystallography is the branch of science devoted to the study of molecular and crystalline structure and properties. The word ''crystallography'' is derived from the Ancient Greek word (; "clear ice, rock-crystal"), and (; "to write"). In J ...

. It is a crystalline form, twin-crystal or double

crystal A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macros ...

(such as chiastolite). It is crystallographic twin according to the spinel twin law and is seen in octahedral crystals or

mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2011): Mi ...

s such as

diamond Diamond is a Allotropes of carbon, solid form of the element carbon with its atoms arranged in a crystal structure called diamond cubic. Diamond is tasteless, odourless, strong, brittle solid, colourless in pure form, a poor conductor of e ...

and spinel. The twin law name comes from the fact that is commonly observed in the mineral spinel. A version with five units about a common axis is called a fiveling. ''Macle'' is an

old French Old French (, , ; ) was the language spoken in most of the northern half of France approximately between the late 8th heraldic term for a voided Lozenge (shape)">lozenge (one

shape within another). Etymologically the word is derived from the Latin ''macula'' meaning spot, mesh, or hole.

Bibliography

* Georges Friedel (1904) "Étude sur les groupements cristallins", ''Extrait du Bulletin de la Société de l'Industrie minérale'', Quatrième série, Tomes III e IV. Saint-Étienne, Société de l’Imprimerie Théolier J. Thomas et C., 485 pp. * Georges Friedel (1920) "Contribution à l'étude géométrique des macles", ''Bulletin de la Société française de Minéralogie'' 43: 246-295. * Georges Friedel (1926) ''Leçons de Cristallographie'', Berger-Levrault, Nancy, Paris, Strasbourg XIX+602 pp. * Georges Friedel (1933) "Sur un nouveau type de macles", ''Bulletin de la Société française de Minéralogie'' 56: 262-274. * J.D.H. Donnay (1940) "Width of Albite-Twinning Lamellae", ''Am. Mineral.'', 25: 578-586.

References

Crystallography fr:Macle (cristallographie) {{Crystallography-stub

Bibliography

See also

References