How Precious Gems and Stones Form

Gems and stones form beneath the earth and are brought to the surface either by mining or by natural earth processes including faulting, folding, uplifts, or volcanic activity. Generally, crystals form based on different factors like their material, temperature, pressure, time, and space present. We’ll go into some more detail below.

How do you mine crystals?

To find these items, miners must typically look for the deposits. In the cases of diamonds, the process of pit mining is used where large machines, hydraulic shovels, and trucks recover the stones from pipes. Mining for other gems, such as colored gemstones, involves a different process and is difficult and expensive because the deposits of precious stones are scattered throughout a large section of rock and tend to be small.

The environment beneath the surface

The Earth’s crust is located from about 3 to 25 miles beneath the surface. After this zone is the mantle, which is roughly 1,800 miles thick and makes up about 83 percent of the volume of the planet. This area is made up of molten rock, which is in constant movement, and where these two zones meet, there are high pressures and temperatures. Continental plates floating on the mantle crash into each other and either push up to create mountains or are pushed down during the interaction. This creates friction and pressure and generates wear, breaking rocks free.

Once these rocks are loose, their chemistry changes if they’re in the perfect environment for the creation of future precious gems. The lower surfaces of the earth will house cavities where magma fluids escape through the fractures. The chemical-rich fluid along with the space in the cavities and the mixture of high temperature and pressure is ideal for crystal formation. With time, the cool-off will create crystallization.

Different processes of formation for different stones

According to gemstone aficionado Howard Fensterman , not all gemstones or minerals are created the same way, or with the same ingredients. Igneous gemstones, for example, are formed in the Earth’s mantle. Diamonds are a perfect example: these crystallize in the magma underneath the crust and have a different chemical composition that geologists believe comes from the depth of 110 to 115 miles beneath the surface of the planet. The environment in this area is of high temperature, creating a highly fluid magma. As this liquid moves forcibly, fast, and violently through the crust, rock is dissolved and carried to the surface. The high speed causes the diamonds to remain intact.

Other stones form through the process of hydrothermal creation. During this process, water that is highly saturated with different types of minerals moves through fractures and cracks. Minerals begin to crystallize as the cooling process takes place. Emeralds form during this process, for example.

The most common process for stone creation is the metamorphic process. Metamorphic rock changes with a combination of temperature, pressure, and minerals. The transformation takes place thanks to the influence of such factors similar to that of igneous rock, except that in the metamorphic process, melting during the formation does not take place. What this means is that the change occurs while the rock is in a solid state. Although this is composed of ordinary rock, the precious nature of the end-product leads to minerals that only form under the special metamorphic conditions, thus making the result uncommon.

This process of crystallization and formation for precious stones is complex and beautiful, thus attracting many enthusiasts that collect these items and study their creation process and natural beauty.