Rainbow Moonstone is a member of the feldspar family, more specifically it’s a plagioclase feldspar, and it’s also considered to be the white variety of Labradorite. Labradorite and Rainbow Moonstone share the characteristic of Labradorescence, which is a very particular play of light off the surface of these crystals. Ironically, these flashes are predominantly blue when they manifest in Rainbow Moonstone, where Labradorite commonly has a wider variety of colorful flashes. Being a part of the feldspar family means that Rainbow Moonstone is actually closely related to traditional Moonstone in its many varieties, which is also a member of the feldspar family. Most Moonstone has a play of light known as adularescence, which is a reflection of light on the surface of the stone that can be either blue or white. Another member of the feldspar family is Sunstone, much like its relatives it also has a play of light called aventurescence. This effect resembles golden or rainbow flecks of glitter under the surface of these crystals. Sunstone can often grow very closely together with Moonstone varieties such as Peach Moonstone or Black Moonstone, creating a combination Sunstone Moonstone that has both the notable adularescence of Moonstone and the aventurescence of Sunstone. Even with such a flashy family, Rainbow Moonstone stands out with its stark white color and unique flash patterns that make it distinctly separate from both Labradorite and Moonstone.