CRYSTAL TWINNING Meaning and
Definition
-
Crystal twinning refers to a phenomenon observed in crystals where two or more crystal structures grow together to form a singular crystal. It occurs when two or more crystal lattices are intergrown in a specific pattern or orientation. This intergrowth can be of various types, leading to distinct twinning structures.
In crystal twinning, the crystal lattice planes of the two or more crystals coincide and are oriented in a predictable manner. The twinning can manifest in several ways, with the most common being contact twins, where the individuals share a common boundary. Another type is penetration twins, where one crystal is embedded within another crystal. Additionally, multiple twins occur when more than two individuals are involved.
Twinning is often the result of internal stress within the crystal during its formation, which can cause a deviation from the usual crystal growth patterns. The twinning process helps to relieve this stress and allows the crystal to achieve a more stable configuration. The twinned crystals can exhibit various physical properties and optical effects, such as striations, lamellae, or patterns of light interference.
Crystal twinning is an essential area of study in mineralogy and crystallography as it provides valuable insights into the atomic arrangement and growth processes of crystals. It also plays a crucial role in understanding the properties and characteristics of minerals. By analyzing and classifying twinning patterns, scientists can gain a better understanding of crystal formation, deformation, and transformations, ultimately aiding in the identification and characterization of minerals.
Etymology of CRYSTAL TWINNING
The word "crystal twinning" has its origins in the field of mineralogy, which deals with the study of minerals and their properties.
The term "crystal" stems from the Greek word "krystallos", meaning "ice" or "clear ice". Initially, the word was used to describe transparent quartz crystals, which were believed to be a form of extremely cold ice due to their clarity. Over time, the term expanded to encompass other types of minerals with a regular atomic structure and well-defined geometric shapes.
The word "twinning" in the context of crystals refers to a phenomenon where two or more individual crystals are joined together in a specific orientation. This occurs during the crystal's growth process when multiple crystals form simultaneously and intergrow, resulting in a unique shared lattice structure. The name "twinning" is derived from the Old English word "twinnian", meaning "to separate into two.
