Crystal twinning
Videos
Crystal twinning occurs when two or more adjacent crystals of the same mineral are oriented so that they share some of the same crystal lattice points in a symmetrical manner. The result is an intergr
Quartz – Japan twin
30° twin of staurolite
90° twins of staurolite
Iron pyrite cross twin
Macle
Videos
Macle is a term used in crystallography. It is a crystalline form, twin-crystal or double crystal. It is crystallographic twin according to the spinel twin law and is seen in octahedral crystals or mi
Crystal twinning
…develops in a crystal in response to a shear stress, and is an important mechanism for permanent shape changes in a crystal. Twinning, a version of macle, is a form of symmetrical intergrowth between two or more adjacent crystals of the same mineral. It differs from the ordinary random intergrowth of…
Macle formed by the merger of three pyrite crystals.