How is Moonstone Formed?

Moonstone is a beautiful and mysterious gemstone that has captivated people for centuries. But where does moonstone come from and how is this luminous stone created?

Moonstone belongs to the mineral family of feldspars. Feldspars make up about 60% of the Earth’s crust and moonstones are a type of feldspar called adularia, which has a pearly sheen. Moonstone deposits have been found all around the world, but the primary source locations are Sri Lanka, India, Madagascar, Myanmar, and Tanzania.

The formation process of moonstone begins deep underground. When molten magma from volcanoes cools far below the Earth’s surface, gases and liquids become trapped inside the magma. This causes small bead-like formations. Moonstone crystallizes within these cavities, forming tiny shimmering orbs. This gives moonstone its distinctive appearance – a velvety glow with a lunar sheen.

As the moonstone develops over millions of years, bits of other minerals and metals become trapped inside the stone. These inclusions give moonstone its signature bluish sheen. The most prized moonstones exhibit adularescence, an optical phenomenon where light is scattered from below the surface to create a moonlight-like glow.

Plate tectonics eventually push the moonstone deposits up closer to the surface where they can be mined. Moonstones are extracted from mines in sheeted vein formations. Miners look for seams of moonstone embedded between layers of other igneous and metamorphic rocks.

The unique glow of moonstone comes from the mineral’s layered structure. Light enters the stone and refracts off the internal layers and inclusions. The refracted light scatters and creates the appearance of billowing clouds across the surface of the gem. This distinctive optical property is what makes moonstone shine with such mystery and allure.

Once extracted, moonstones are cut and polished to enhance their dreamy visual effect. The way a moonstone is cut can maximize or dampen its adularescence. Cabochon cuts, with rounded tops and flat backs, are ideal for showing off a moonstone’s radiance. Other popular cuts are the cat’s eye and star moonstones which display dazzling optical effects.

From volcanic magma chambers to jeweler’s workshops, moonstones take an incredible journey during their formation. These hypnotic gems glow with otherworldly light and their origins are as fascinating as their lunar beauty. The rarity and specific geology needed to create moonstones adds to their mystique as one of the world’s most magical gemstones.