Some people think diamonds, rubies, and sapphires are formed when lava meets water to create a large, clear lake. Others believe that these stones are formed as the sedimentary rock is exposed to the elements over a long period of time. Still, others believe that they are formed when one mineral is melted, and another is transformed into a new mineral. But what if I told you that there is an even simpler theory for these beautiful stones? One states that they are formed when a high-pressure metamorphic rock experiences a sudden change in temperature.
Before getting to the science behind the process, you must first understand what exactly a gemstone is. Gemstones are natural crystalline materials that are formed in the Earth’s crust. The most common type of gemstone is a mineral, which is a naturally occurring inorganic solid that is chemically pure and crystalline in its natural state. For example, diamonds, rubies, emeralds, sapphires, and opals are all minerals. However, not all minerals are gemstones. Some minerals are considered to be industrial minerals, which are used in the production of many products, such as glass, iron, steel, or cement. Others are considered to be gemstones but have different uses.
How are gemstones formed? Gemstones are naturally formed by processes such as heat and pressure. While most people think of precious stones as forming over millions of years, these natural processes can take place within a few hundred years. The most famous gemstone-forming process is the formation of rubies and sapphires from kimberlite or lava. Still, a number of other processes can form gemstones, ranging from simple silicon dioxide to diamonds.
Gemstones are formed by processes in which magma is solidified into solid rock. By far the most common process of gem formation, magma is the molten rock that is formed beneath the crust of the Earth. The “stuff” of which gemstones are made is magma, which is a rock that is hotter than the rock surrounding it. Magma is denser than any other type of rock (like granite or sandstone), and when magma cools, it crystallizes into a solid.
The most common minerals in the earth’s crust are quartz, feldspar, mica, and quartzite. These are all silicate minerals. Silicate minerals are compounds containing silica, and the most common silicate minerals are feldspars and quartz. There are various stages of the formation of silicate minerals. The first step in the formation of silica-rich rocks is the metamorphism of existing igneous rocks. By applying heat, pressure, and/or water, excess silica present in these rocks is changed into quartz. In the next step, this quartz subsequently undergoes alteration. If this interaction of heat, pressure, and water is continued, the quartz becomes more altered.
Gemstones are a group of minerals that are formed by certain types of rocks from elements found in nature. The formation process of these minerals is multi-step and involves many chemical reactions. The ring around each stone is called a “mold.” The first step involves the mineral that is forming the gemstone dissolving in the water. When this happens, the water becomes more acidic. This is important because the acid causes the crystals to grow faster. The second step is the gentler action of carbon dioxide and calcium carbonate in the water. This causes the crystals to grow much faster. The third step is the chemical reaction between carbon dioxide and calcium carbonate. This produces the gemstone.
The interaction of heat and pressure can result in some pretty interesting things, and the weathering of stones is a classic example. The term “weathering” was coined by one of the fathers of modern geology, James Hutton, and if you’re paying attention, you’ll notice that its meaning is not at all obvious. Hutton and his contemporaries believed that the earth’s surface was constantly changing. The way it changed was through erosion and deposition, or the wearing away and building up of rocks.
Gemstones are formed by nature, and they come in many forms. Most of us think of diamonds when we think of gems, but while a diamond is a very rare gem, there are more than a few types of gemstones that are quite common. And finally, it turns out that some gemstones are formed under extreme conditions.