How Are Gemstones Created?

Minerals are formed in the ground under a wide range of environmental conditions. Gemstones are often created in the earth's crust, the planet's outermost layer that can be found anywhere from three to twenty-five miles below the surface. The mantle, which accounts for around 80% of the earth's volume, is the only place where jewels besides diamonds and peridot may form. Magnesium-rich magma makes up the bulk of the mantle, which is otherwise solid.

All gems are extracted from the crust, although some are formed in the mantle. Igneous rock, metamorphic rock, and sedimentary rock are the three types of rock that make up the crust. The formation process of the rock is referred to by these specialised terminologies. Gemstones can only be found in one type of rock, whereas others can be found in more than one.

Magma cools and hardens, a process known as igneous. Typically, volcanic pipes are the means by which mantle magma is brought up to the crust. As soon as it hits the surface, it cools and becomes lava. On the other hand, minerals can form from magma if it cools slowly enough in the crust. When pressure rises, this pegmatitic fluid can seep into the rocks around it and often undergoes chemical reactions with them. The chrysoberyl group, all quartz (including amethyst, citrine, and ametrine), beryl (emerald, morganite, and aquamarine), garnet, apatite, diamond, moonstone, spinel, tanzanite, tourmaline, topaz, and zircon are all gemstones derived from volcanic rock.

When igneous rock reaches Earth's surface, it is subjected to weathering and erosion, which break it down into smaller pieces that either settle to the surface or are transported by wind and water. These sediments accumulate over time to form strata on land or in the sea. Sedimentary rock is formed when sediments are compressed under the weight of heavier strata, which also leads to other chemical and physical changes, like lithification. Sedimentary rock, such as that which is typically found in deserts, can also be formed through evaporation. Jasper, malachite, opal, and zircon are just a few of the gemstones commonly found in sedimentary rock.

Igneous and sedimentary rocks and minerals are subjected to heat and pressure that may alter their chemistry and crystal structure due to intrusive magma (contact metamorphism) or tectonic plate interactions (regional metamorphism). When this happens, metamorphic rock is formed. Beryl, jade, turquoise, spinel, lapis lazuli, ruby, sapphire, and zircon are all types of gemstones that are commonly found in metamorphic rock.

The rock cycle refers to the continuous process of change that occurs inside rocks and minerals. It is possible for igneous rock to undergo metamorphism or sedimentation. In addition, the sedimentary rock can undergo metamorphism or igneous transformation. In addition, metamorphic rock can evolve into either igneous or sedimentary rock. Yet you must be patient.

Gemstone Formation 

Igneous

These elements originate from the Earth's interior (Diamonds, Ruby, Sapphires, Peridot). They are made when magma cools in the air or underground. Sediments are formed as something erodes and settles to the ground. If a molten rock is allowed to cool and solidify at a slow rate, the resulting crystals may be of a bigger size.

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In the Earth's Mantle, Igneous Gemstones Form

Even though we don't know a lot about the mantle of the Earth, there is evidence that certain gemstones are formed there. High heat is required for this.

Diamonds and peridots stand out as two of the most famous gemstones formed in the Earth's mantle. Geologists have analysed peridot deposits in Arizona and concluded that they formed on rocks that were free-floating in the earth's mantle at depths of up to 55 miles. An enormous eruption pushed them closer to the surface, where erosion and weathering eventually brought them to light.

Still, we have a deeper comprehension of diamonds now than ever before. Underneath the crust, in the magma, diamonds form. However, the chemical makeup of these structures is unique. Researchers have determined that it originates between 110 and 150 miles below the planet's surface. At such a depth, the magma is extremely fluid, and the temperatures are extremely high.

This magma has the potential to cause volcanic eruptions that are substantially more rapid and powerful than average. Magma melts and fragments rocks during an eruption, bringing them to the surface with it.

Most diamonds wouldn't make it if the magma rose slowly. The diamonds would either evaporate or re-crystallize as graphite due to the pressure and fluctuating temperatures. Because of the rapid ascent of the magma, however, the diamonds don't have time to metamorphose or evaporate, and thus they retain their diamond shape.

Crystals are easily fractured when the crust undergoes abrupt and jarring changes. A substance seeps into the cracks and crystallises when growth conditions are met. This helps seal the fractures, which speeds up the healing process. Even after healing, the tiny holes can be seen, making them look like fingerprints.

When gemstones form, how do they eventually make their way to the top? It's amazing that they can be mined at all, given that they form so deep underground. While some of these materials are brought to the surface by volcanic eruptions, the vast majority are carried there through erosion and the development of mountains.

Hydrothermal

Gemstones are created in a manner analogous to that of rock candy when mineral-rich bodies of water are allowed to cool.

Hydrothermal Gemstone Creation

In comparison to the last example of making rock candy, this method is the most similar. Mineral-rich, supersaturated water is forced upward through geological crevices. Other minerals begin to crystallise as this solution cools.

Columbia is home to the world's most significant hydrothermal discoveries. The Muzo Emerald mine, to be precise. The stunning colour of the Emeralds found in this region is due to the high Chromium content of the hydrothermal deposits in this area.

The hydrothermal mineral vein is depicted in the figure below. Water solution cools inside the fracture in the surrounding rock, forming this vein.

Metamorphic

These diamonds are transformed by high temperatures and pressures, as the name suggests. (Pink, Blue, and Yellow Sapphires, Rubies, and Green and Red Garnets). Any rocks that have been altered by heat and/or pressure to generate new rocks with new minerals fall under this category, whether they were originally igneous or sedimentary rocks. It is because of this that gems can be grown inside of them. Mica schists, which have their origins in clay and mudstones, are where garnets are forged. Due to the high temperatures and pressures required to transform limestone into marble, the gemstone rubies can also be found within the original limestone.

Gemstone-quality minerals may be found at or near the earth's surface, in deep underground deposits, or eroded off rocks and carried by rivers to the ocean.

Metamorphic Gemstone Creation

Metamorphic processes are responsible for the formation of the vast majority of gemstones. This happens when minerals are compressed and heated to extremely high temperatures, as is often the case when two tectonic plates move beneath each other. Minerals are pressed together and change into other minerals, sometimes without melting.

Sedimentary

Gems are formed when sediments are deposited by water (Malachite, Azurite, Opal). Weathering causes rock fragments to accumulate and compress, forming rocks (sand or mud). These things could then be reburied under the ground. The majority of opal mined in Australia comes from sedimentary rocks.

Sedimentary Gemstone Creation

Water combines with minerals at the earth's surface to form sedimentary gemstones. The water eventually seeps down into the earth's crevices and deposits layers of minerals. This is the process that gives rise to precious stones like azurite, malachite, and opal. When water and silica are combined, the silica solution settles, generating small spheres of silica that stack on top of each other to produce opal.

Create Your Own Crystals

Creating crystals on your own is a great method to learn about the crystal growth process. Sugar can be crystallised to make rock candy, which is the quickest and easiest method.

Put as much sugar as you can handle into a pot of boiling water and stir. When it stops dissolving altogether and starts to settle to the bottom, you know you've reached maximum concentration. There is no more sugar water to take in. Super-saturation refers to this state.

Afterwards, you should get the water boiling. When a substance boils, the saturation level shifts. There is no longer any supersaturation in the solution. There's room for a lot more sugar today. The solution is to increase the amount of sugar used until the supersaturation point is once again reached.

The saucepan should be taken off the heat. Once the water returns to normal temperature, it will be able to suspend the same quantity of sugar as before. In order to use the solution, the sugar surplus must be removed. And as it does so, it crystallises.

String the sugar water up so the crystals can develop vertically. The string can be kept taut by placing a weight at its base. Changes in the crystals can be seen every few minutes, even if the process itself is too slow to see without a microscope.

After the sugar solution cools to room temperature, sugar crystals will form on the string. Re-acquired supersaturation of the water is imminent.

Magma Crystallisation

Many elements can be found in magma. Minerals are formed when melted substances cool down to room temperature. For each new mineral that forms, the accessible components shift according to the new temperature and pressure (due to the fact that some substances are crystallised). Minerals crystallise out of magma at different stages as their temperature, pressure, and chemical composition shift.

Aggregates

Crystals won't form, though, unless everything is precisely right. When magma cools, it forms an aggregate, which is a solid mass of tiny crystals that interlock with one another.

Phenocrysts

It's possible to get good crystal growth from just one material in certain conditions. The magma will then find a crack in the crust and rush to the surface before any more crystals have a chance to form. It is not possible for crystallisation to occur at these pressures and temperatures. The remaining magma instead solidifies into granular rocks, with the original crystals dispersed throughout. Phenocryst is the term for such objects.

Waterborne Minerals Can Provide Gem Colours

Minerals integral to the chemical composition of several gemstones are the primary source of their colour. 

For instance, the copper found in water is responsible for the colour of turquoise, azurite, and malachite. In order to form azurite or malachite, the copper-rich water must first flow through a bed of limestone. Throughout its journey, the water must also absorb some phosphorus in order to turn turquoise.

How Can Crystal Growth Interruptions Impact Gem Formation?

Some might assume that enough time has passed in the geological past for crystals to form. And in this extremely turbulent setting, doors open and close all the time. When crystals develop, the channel carrying mineral-rich fluid into the cavity frequently closes. Every further development has to halt.

There will be a return to expansion if the door is opened again. Its intermittent development is typically not noticeable in a crystal. There are, however, occasions where it has a discernible impact.

Colour Zoning

It's not uncommon for there to be a modest variation in chemical makeup between growing layers. Crystals may exhibit colour zoning if this occurs.

Twinning

There are times when the new layers are laid out in a way that is counter to the original. Twisting of the chromosomes results.

Parting

In some twinned crystals, the newly formed layers may not fully bind with one another. The layers of a star ruby didn't connect properly, as evidenced by the presence of separating.

Crystal Specimens Made Out Of Many Minerals

It is possible for a completely distinct mineral to crystallise over an existing substance even if a previously blocked route reopens and fluid once again enters a cavity. The fluid solution's temperature, pressure, and chemical composition can all shift over time. Within hollow, different mineral crystals will form depending on the environmental circumstances. The first layers of a deposit are often covered by a different mineral when it is excavated.

Inclusions

One of the reasons gemstones include inclusions is because of internal temperature and pressure shifts. It's possible for a new crystal to begin growing on top of an existing, larger crystal only to have its growth process halted. To the extent that the original crystal can continue to develop, it will eventually smother the more recent one.

It's not uncommon for two distinct minerals to form simultaneously. One will eventually consume the other if it gets a head start and grows more rapidly. This is the process by which pyrite crystals become embedded within emeralds.

The presence of chemical impurities within a crystal is also possible under certain circumstances. The impurities can form crystals inside the host crystal if the temperature and/or pressure are altered. (In effect, the host crystal works as a cavity storing materials that just need the correct conditions to crystallise itself). This is the process by which rutile develops within crystals of quartz and corundum.

Phantoms

Phantom crystals or inclusions can happen very seldom. This occurs when a new layer of crystals forms on top of a previously transparent one. A quartz crystal, for instance, might have a thin coating of feldspar over it. Then the environment shifts once more, and the original transparent crystal resumes its growth. This time, though, quartz has formed a new covering over the feldspar. The resultant gem reveals the shape of the secondary crystal layer, but it's so faint that it's almost invisible, earning it the moniker "ghost" crystal.

Healing Fractures

Many crystals are shattered as the crust undergoes its jarring and violent changes. The material can infiltrate into the cracks and crystallise if the right circumstances are met. What this does is grow the broken crystal back together, thereby "healing" the fracture. 

Yet, these fractures never fully mend. The void is filled by tiny gas cavities. A healed fracture is the term for this sort of enlargement. Gemologists also term these inclusions "fingerprints" due to the resemblance the remaining fine cavities may have to fingerprints.

Strain

Many crystals are compressed beyond their normal size by the enormous pressures in the underground environment of gem production. A stone's fragility can be further exacerbated by this stress. This stress could be present in diamonds, tourmalines, and even garnets. A great number of factors have tried breaking these stones by setting them on a lap, but all have failed. The internal pressures of the stone cause it to detonate spontaneously.

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Gem Formation And Geological Processes

Gemologists have made significant progress in their understanding of mineral crystallisation. Several of these natural mysteries have been uncovered thanks to developments in geology and synthetic gem production. (Laboratory gem production is accomplished by simulating circumstances found underground, albeit on a much smaller scale and with much less time invested).

The three types of rock formation processes typically taught in schools are:

• Heat is used to form igneous rocks deep within the ground.
• When minerals are subjected to high temperatures and pressure, new rock formations called metamorphic rocks can occur.
• Sedimentary rock is a rock type that is formed when sediment is deposited.

Geologists today typically use a four-step model to explain rock formation:

• Melting rock and its constituent fluids
• Environmental modifications
• Water on the surface
• The creation of gems in the earth's mantle

In this post, we'll examine the role that each of these plays in the gem-making process.

Regardless of what we think we know, the production of minerals and gems is anything but simple or easy.

There's no denying the beauty of jewels, diamonds, and crystals, but who or what creates them? Geology can explain that. That's the branch of science that examines the composition and history of the rocks and other solids on Earth. You'd be surprised to learn that those rough hunks of the earth have more in common with priceless jewels than you might imagine.

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Conclusion

Gemstones are made in the Earth's crust, three to twenty-five miles below the surface. Magnesium-rich solid magma dominates the mantle. Igneous, metamorphic, and sedimentary rocks comprise crustal rock. Gemstones are exclusive to one rock type. Minerals can form in the crust if magma cools slowly enough.

Gemstones form when mineral-rich water cools, like rock candy. Columbia is home to some of the world's most important hydrothermal finds, including the Muzo Emerald mine, whose high Chromium content gives the Emeralds their beautiful colour. As its name implies, extreme heat and pressure generate these diamonds in igneous or sedimentary rocks. Mica schists' molten lava forms garnets in Earth's mudstones and clays. Gemstone-forming minerals can be found on the surface, underground, or in rivers.

Silica dissolved in the water settles into tiny spheres that can be stacked to produce opal. Sugar crystallises into rock candy, a wonderful way to learn about crystal growth. Magma has many components, and sugar water strings into crystals every few minutes. Crystal formation from magma depends on temperature, pressure, and chemical composition.

Content Summary

• Minerals are formed in the ground under a wide range of environmental conditions.
• Gemstones are often created in the earth's crust, the planet's outermost layer that can be found anywhere from three to twenty-five miles below the surface.
• Although some are formed in the mantle, all gems are extracted from the crust.
• Igneous rock, metamorphic rock, and sedimentary rock are the three types of rock that make up the crust.
• Beryl, jade, turquoise, spinel, lapis lazuli, ruby, sapphire, and zircon are all gemstones commonly found in metamorphic rock.
• Even though we don't know much about the mantle of the Earth, there is evidence that certain gemstones are formed there.
• Diamonds and peridots stand out as two of the most famous gemstones formed in the Earth's mantle.
• Geologists have analysed peridot deposits in Arizona and concluded that they formed on free-floating rocks in the earth's mantle at depths of up to 55 miles.
• Researchers have determined it originates between 110 and 150 miles below the planet's surface.
• Most diamonds wouldn't make it if the magma rose slowly.
• Because of the rapid ascent of the magma, however, the diamonds don't have time to metamorphose or evaporate, and thus they retain their diamond shape.
• Amazingly, they can be mined because they form so deep underground.
• Gemstones are created in a manner analogous to that of rock candy when mineral-rich bodies of water are allowed to cool.
• Columbia is home to the world's most significant hydrothermal discoveries.
• The stunning colour of the Emeralds found in this region is due to the high Chromium content of the hydrothermal deposits in this area.
• As the name suggests, these diamonds are transformed by high temperatures and pressures. 
• Metamorphic processes are responsible for the formation of the vast majority of gemstones.
• The majority of opal mined in Australia comes from sedimentary rocks.
• Water combines with minerals at the earth's surface to form sedimentary gemstones.
• This process gives rise to precious stones like azurite, malachite, and opal.
• Creating crystals on your own is a great method to learn about the crystal growth process.
• The solution is to increase the amount of sugar used until the supersaturation point is again reached.
• String the sugar water up so the crystals can develop vertically.
• After the sugar solution cools to room temperature, sugar crystals will form on the string.
• Re-acquired supersaturation of the water is imminent.
• Minerals crystallise out of magma at different stages as their temperature, pressure, and chemical composition shift.
• There will be a return to expansion if the door is opened again.
• Its intermittent development is typically not noticeable in a crystal.
• There are, however, occasions where it has a discernible impact.
• It's common for there to be a modest variation in chemical makeup between growing layers.
• Crystals may exhibit colour zoning if this occurs.
• There are times when the new layers are laid out in a way that is counter to the original.
• Twisting of the chromosomes results.
• In some twinned crystals, the newly formed layers may not fully bind.
• The layers of a star ruby didn't connect properly, as evidenced by the presence of separating.
• A completely distinct mineral can crystallise over an existing substance even if a previously blocked route reopens and fluid once again enters a cavity.
• The fluid solution's temperature, pressure, and chemical composition can shift over time.
• The first layers of a deposit are often covered by a different mineral when it is excavated.
• A new crystal can begin growing on top of an existing, larger crystal only to have its growth process halted.
• To the extent that the original crystal can continue to develop, it will eventually smother the more recent one.
• It's common for two distinct minerals to form simultaneously.
• This is the process by which pyrite crystals become embedded within emeralds.
• The presence of chemical impurities within a crystal is also possible under certain circumstances.
• This is the process by which rutile develops within crystals of quartz and corundum.
• Phantom crystals or inclusions can happen very seldom.
• Many crystals are compressed beyond their normal size by the enormous pressures in the underground environment of gem production.