孪晶 Crystal twinning
（重定向自Penetration Twin）
![钠长石的孪晶结构示意图](/Images/godic/202502/01/Twinned_crystals_of_Albite1654.png")
![硫化汞的孪晶结构](/Images/godic/202502/01/Cinnabar_twins1654.jpg")
![孪晶接合面在镀锌表面清晰可见](/Images/godic/202502/01/Galvanized_spangle1655.jpg")
![金粗石相的孪晶结构](/Images/godic/202502/01/Rutil_twin1655.jpg")
孪晶是指：由两个或者两个以上同种晶体构成的﹑非平行的规则连生体。又称双晶。在构成孪晶的两个单晶体间﹐必然会有部分的对应晶面﹑对应晶棱相互平行﹐但不可能全部一一平行﹐然而它们必可通过某一反映﹑旋转180°或者反伸（倒反）的对称操作而达到彼此重合或者完全平行。
Penetration Twin
中文百科
英语百科
Crystal twinning 孪晶
（重定向自Penetration Twin）
![Diagram of twinned crystals of Albite. On the more perfect cleavage, which is parallel to the basal plane (P), is a system of fine striations, parallel to the second cleavage (M).](/Images/godic/202502/01/Twinned_crystals_of_Albite1655.png")
![Quartz - Japan twin](/Images/godic/202502/01/Quartz_Japan_Twin_Huaron_Peru1655.jpg")
![Twinned pyrite crystal group](/Images/godic/202502/01/Pyrite_606081655.jpg")
Crystal twinning occurs when two separate crystals share some of the same crystal lattice points in a symmetrical manner. The result is an intergrowth of two separate crystals in a variety of specific configurations. A twin boundary or composition surface separates the two crystals. Crystallographers classify twinned crystals by a number of twin laws. These twin laws are specific to the crystal system. The type of twinning can be a diagnostic tool in mineral identification.