What is crystal structure of amethyst?

Amethyst is a variety of quartz, which crystallizes in the trigonal system. Its crystal structure is characterized by a hexagonal arrangement of silicon and oxygen atoms, forming a continuous framework of SiO₂ (silicon dioxide). The purple color of amethyst is due to the presence of trace amounts of iron and other impurities, which can create color centers in the crystal lattice. Overall, its unique structure contributes to its beauty and popularity as a gemstone.