Exsolution lamellar structure causes of iridescence in labra

Transmission electron microscopy(TEM) and STEM reveal the exsolution lamellar structure in labradorite,which is responsible for the iridescence of labradorite.The labradorite is made up of calc-poor and calc-rich plagioclase,and its thickness is mainly controlled by calc-rich plagioclase.The more the calc content,the thicker the lamellar,and the longer the wavelength of the interference color.Furthermore,the increasing speed of calc-rich plagioclase will surpass that of the calc-poor one.The selected area electron diffraction(SAED) shows that the direction of exsolution lamellar structure is(153),which is nearly parallel to(010).The uniform interference color may have different calc contents and exsolution directions,varying from place to place and from environment to environment.