How Are Gemstones Formed? There are over 4,000 known minerals on Earth, and some of the most valuable are known as gemstones. Gemstones most often look like any other plain stone or mineral when they are first unearthed, but after they have been cleaned, polished, and prepared for display, they reveal their natural brilliance, appearing in many beautiful colors and patterns. In this article, we'll discuss how gemstones are formed by the Earth's natural processes, as well as some of the differences between various types of gemstones. What Are Gemstones? Before we discuss how gemstones are formed, we'll first better define just what gemstones are. Gemstones are minerals, or inorganic solids that have a particular molecular pattern. Minerals are made up of repeating chains or 3D arrays of molecules for individual elements, and are usually formed in confined areas like lava flows or in sediment-rich riverbeds. The major classes of minerals include silicates, oxides, sulfides, sulfates, carbonates, and halides. Gemstones and other minerals are classified according to their physical properties, including hardness, color, density, luster, and magnetism. How Are Gemstones Formed? As minerals, gemstones are most often formed when molten rock (magma) cools and then hardens into deposits. Most gemstones are formed in the top layer of the Earth's surface, the crust, anywhere from 3 to 25 miles deep. The only known exceptions to this are diamond and peridot, which form in the layer beneath the crust, the mantle. The Earth's crust is made up of three different types of rock, which are classified by the natural processes that forms them: Igneous – created by the circulation and solidification of magma Sedimentary – created when pressure compacts multiple types of minerals together Metamorphic – created when heat and pressure transform one type of mineral or rock into another type The igneous mineral creation process occurs when magma beneath the Earth's surface rises from the mantle to the crust. If the magma escapes to the surface, it becomes lava. If it gets trapped beneath the surface and cools in the mantle, however, it will turn into mineral deposits, which might include gemstones such as diamond, garnet, and moonstone. Sedimentary rocks are created when the forces of erosion reduce igneous minerals to smaller particles, which are then washed or blown away. When thick enough layers of these particles build up on land or under water, the pressure within can cause physical and chemical changes in the mineral particles, causing them to form new compounds. Sedimentary gemstones include jasper, opal, and zircon.
If igneous or sedimentary rocks come into contact with intrusive magma or certain tectonic activities, they can be further changed and form metamorphic gemstones, including turquoise, rubies, and sapphires. The mineral creation process is long and complex, and different types of minerals can be changed into other types given enough time and the right conditions Mining For Gemstones Once deposits of gemstones have formed, they can be found in the Earth's crust and mined. Once they have been removed, they are polished, tested, and cleaned, a process that changes them from just another unpolished rock in the ground to the beautiful diamond earrings, alexandrite rings, and other precious jewelry pieces that gives gemstones their value.