Crystals in the Earth System

Crystals are found in all spheres of the Earth: the atmosphere, the biosphere, the hydrosphere, and the lithosphere. Crystallization occurs in the ground on which we walk, in the weather we experience, in the things we eat, and in our own bodies. Crystals themselves form based on the atomic structure of the element from which they are formed. While these naturally occurring gems and minerals are resources that provide entertainment, beauty, and technological advances, there are also issues and problems that are associated with obtaining these resources.

Minerals and gems are solid substances with a crystalline structure. According to Merriam-Webster, a crystal is “a body that is formed by the solidification of a chemical element, a compound, or a mixture and has a regularly repeating internal arrangement of its atoms and often external plane faces.” This means that in order for crystals to form, the atoms of the dissolved substance must arrange themselves in regular patterns. Additionally, for crystals to grow, the atomic pattern arrangement must repeat. This will only occur when a dissolved substance, the solute, has supersaturated its medium. Supersaturation is reached when the maximum amount of solute that can be dissolved at a given temperature is exceeded. As the solution is cooled or evaporated, the solute precipitates out of the solution and crystallization begins.

The first stage in crystal formation is nucleation. Vekilov, a Professor at University of Houston, describes the process of nucleation according to classical nucleation theory. Vekilov (2007) tells us that nucleation occurs when the first molecules of the dissolved substance come together in a pattern. This process begins the development of the crystal as the liquid solution cools allowing molecules in the supersaturated liquid to collect. The molecules of the substance precipitate out and attach to the crystal nuclei in the repeating molecular pattern. The molecules form a uniform and repeating pattern which continue to grow forming the crystal. Nucleation will not occur without supersaturation of the dissolved substance since there would be no precipitation to form the crystal. Though most minerals crystalize naturally in nature, we do not often see perfectly formed crystals because the ideal growing conditions are not present everywhere.

Cooling rate affects crystal size. When a supersaturated substance cools quickly, the size of any crystal formation will be smaller because the molecules have less time to arrange themselves into patterns as the solute continues to precipitate from the cooling solution. When a substance cools slowly, the size of crystals formed will be larger because the molecules have more time to arrange themselves into increasingly larger patterns. For example, crystals of varying size form in igneous rock as magma cools at varying rates. Lee Lerner, co-founder and senior commissioning editor at LernerMediaGroup, describes how the cooling speed of magma impacts the texture of the igneous rock formed due to the size of crystal formation (2014). Fast cooling magma results in small crystal formation.  Slow cooling magma results in large crystal formation.

Space also affects crystal growth. When little space is available, the substance will develop very tiny patterns of crystal formation.When large space is available, the substance can develop extremely large patterns of crystal formation. Similarly, the length of time crystals are allowed to grow undisturbed will also impact crystal formation. The longer a substance is allowed to crystallize unimpeded, the more crystal formation can occur. In the Cueva de los Cristales in northern Mexico, the largest crystals on Earth are found. Volcanic activity millions of years ago caused a mine to fill with water which dissolved the mineral found in the mine.  The slowly cooling magma near the mine kept the water at a warm 58℃, allowing the mineral to precipitate out so slowly that the crystals were able to form and continue growing for millions of years. (Cave’s mystery now crystal clear, 2007).  Van Driessche et al. (2011) established that a single “gypsum crystal beam of 1-m in diameter formed at 55 °C from a solution [similar to that found in Mexico] … should have been growing for 0.99 ± 0.27 million years.” The slow cooling, coupled with the large space in the mine, allowed extremely large crystals to form.

The lithosphere contains the ground and deeper layers of the planet Earth. The lithosphere contains the surface soil and rocks that make up the ground, hills, and mountains we see as well as the deeper layers of liquid rock below. In the layers of the lithosphere, crystals can be found. In the mantle, cooling minerals precipitate out of the molten rock as it cools.  Lerner (2014) details the Bowen reaction series which explains the order in which minerals crystallize out of magma during the cooling process. The speed at which these crystals form determine the texture of the igneous rock formed.  Pegmatite texture is formed with very large crystals due to extremely slow cooling. Phaneritic texture is formed with visible crystals due to slow cooling. Aphanitic texture contains microscopic crystals produced from intermediate cooling. Glassy texture forms without crystals due to the rapid cooling time of the magma. Magma that cools nearer the Earth’s surface will form smaller crystals since magma near the surface cools faster. This type of igneous rock will more likely be glassy (obsidian) or aphanitic (basalt). Magma that stays deeper within the Earth will cool more slowly allowing larger crystal development. This type of igneous rock will more likely be pegmatite (tourmaline) or phaneritic (granite).

The hydrosphere contains all of the water on the planet whether in solid, liquid or gas form.  Water is essential for life on Earth.  More precisely, freshwater is essential for life on Earth. And, while water covers approximately 71% of the Earth’s surface, most of that liquid water contains dissolved salt. Salt can be found most obviously in the oceans but also in underground deposits where seawater has been trapped. Salt found in deposits below ground formed where seawater was once trapped. When the water evaporated from these underground mines, salt crystals were left behind (Sea Salt vs. Table Salt, n.d.). Other salts form from evaporation at the ocean’s edge.  The practice of harvesting salt from evaporated water has ancient beginnings. “In China as far back as 800 BCE, people evaporated sea water in pans as large as 10 ft. in diameter. Today, large-scale artificial evaporation ponds, also known as salterns or salt pans, are used throughout the world” (Last month’s answer, 2016). Seawater trapped in natural or man-made ponds evaporates leaving the sea salt behind to be harvested. Salt will also seep out of building materials and rock when these materials come into contact with rainwater. Shahidzadeh-Bonn et al. (2008) point out that repeated cycles of dissolution and evaporation of the salt in these materials will lead to damage due to pressure created by the growth of the salt crystals. When crystals begin to form in these materials, the crystals will push again the materials from the inside causing cracks and other damage. While salt is contained in most of the hydrosphere, about 3% of the available water on Earth is freshwater, and most of that small portion of freshwater is frozen. Water itself has a crystalline structure when frozen. Whether frozen on the ground or frozen in the air.

The atmosphere contains all of the air surrounding the planet. The gases that compose the atmosphere extend into the ground as well as surround the Earth. The heating and cooling of the atmosphere move the gasses around the planet creating weather. The atmosphere contains the necessary gasses for respiration of plants and animals. Water in its gaseous state is also found in the atmosphere. When the atmosphere becomes supersaturated with water and the air temperatures cool, water will precipitate out. When the atmosphere is cool enough, the water molecules will begin to gather in a lattice formation creating a repeating pattern of crystals. Brini et al. (2017) explains how the tetrahedral shape of the water molecule “leads to cage-like structuring” and is also responsible for molecular abnormalities that occur with crystalized water (p. 12388). For instance, frozen water expands when crystalized and is less dense than when in its liquid form. However, there is not a single crystalline structure for water.  Brini et al. reports that “There are 17 known crystalline forms of water” (2017, p. 12393). Further, Brini et al. point out that

Snowflake structures are a result of water’s hexagonal symmetries, which are the basis for sixfold directional growth in this plane. Snowflakes start as small six-sided plate crystals or prisms. Depending on the temperature and humidity, they may continue to grow as plates or become needles, stellar plates, or dendrites, among others … Defects in crystal growth lead to the immense variety of snowflake shapes. (2017, p. 12393)

The biosphere contains all the living organisms on planet Earth. From the smallest to the largest, all living things are part of the biosphere. While crystals are not living things, crystals are contained within many of the living organisms on Earth. For example, human balance is achieved due to the development of otoconia, small calcium carbonate crystals found in the inner ear. Lundberg et al. (2015) explain that these crystals are also present in other animals such as zebrafish and mice. They further describe how movement of the crystals in the inner ear acts on hair cells triggering electrical signals which the brain interprets to maintain balance. “Head tilt and linear head motion cause displacement of the otoconial complex, producing a shearing force that deflects the hair bundles and subsequently depolarizes the sensory hair cells. These electrical signals are then relayed to the central nervous system…” (p. 239). However, not all crystals produced by living organisms have such positive characteristics. Nishimura et al. (2016) and Ho-Tin-Noé et al.(2017) investigated cholesterol crystallization and its impact on atherosclerosis development. Atherosclerosis is the buildup of fats and cholesterol on artery walls  forming plaque. The plaque restricts blood flow and can cause pressure and rupturing of the artery leading to blood clots and possible death.

When considering issues and problems associated with crystals in the Earth Systems, they are not difficult to find or understand. Elliot and Bloomberg (2020) explain the rise of public interest in crystals. The demand for crystals has increased due to more interest in crystal near-gemstones, and away from rare, expensive gems. Interest in crystals has also been spurred by numerous celebrity endorsements making claims about the healing benefits of crystals. Technological advances such as rechargeable lithium ion batteries have also added to the demand for crystals (KU Leuven, 2018). As demand has risen the need to increase supply has created problems. Crystals are obtained by mining. The impacts from crystal mining are far reaching and have geological, biological, and political implications.

Damage can include landscape destruction, water contamination, habitat loss, unethical labor practices, and disease. In less industrialized countries, the discovery of crystal deposits can lead to an area becoming an “artisanal mine.” Peter Hobson, staff writer for Reuters explains artisanal mining as “freelance” mining. In many countries, crystal mining is conducted by individuals and small groups.  This type of subsistence mining allows people to harvest the resource with little to no oversight by their governments, an issue that leads to the negative impacts on the land and on the people. An article in NewsRx Health (2018) described the physical impact on an area in the Democratic Republic of the Congo when a deposit of cobalt was discovered. The land became “interspersed with dozens of mine pits where hundreds of [miners] hunt for cobalt.” Cartier, Ph. D. candidate from University of Basel, Switzerland,  similarly describes the resulting destruction of land from artisanal mining in many countries as “pot-holed landscapes” (2010, p. 12). When artisanal mines develop, the miners become so focused on the financial opportunity presented that the long term effects of  mining are overlooked. NewsRx Health and Cartier further explain that people will leave their agricultural responsibilities which can lead to food shortages when farms no longer have enough people to work the land and harvest crops. Cartier further tells how the “unfilled pits that [are created by the miners] nurture the spread of malaria” (2010, p. 13). The pock-marked landscape created by mining activities of people trying to reach the crystal resources destroys habitats of animals and can also leave farmland infertile. Some people in less industrialized countries rely on crystal mining as a way to make money. Without government supervision, even the children are forced to work in unsafe mining conditions. David McKay, owner and publisher of  Miningmx, writes news and analysis related to the African mining sector. McKay (2020) explains the child labor issues found in the Democratic Republic of the Congo. The dust that is created by the excavation required for mining contains contaminants such as graphite and uranium. WebMD Medical Reference explains that breathing these particles can lead to silicosis, a chronic illness caused from breathing crystalline silica dust, which can also lead to lung disease. The problems associated with silicosis could appear within weeks depending on the amount of exposure to the silica dust but also may not appear for decades and access to adequate medical care may not be easily available for miners in these circumstances. The NewsRx Health article further describes finding “more DNA damage in children living in the mining area…[and] increased risk of birth defects” (2018). Cartier states plainly that “Improving environmental sustainability in gemstone mining is not simply about safeguarding virgin landscapes. It is about conserving fragile ecologies that are vital for the present and future livelihood bases of fauna, flora, and humans” (2010, p. 18).

The problems associated with  mining stem from a crystal market that is growing exponentially worldwide due in part to celebrity endorsement but also due to growing technological uses for crystals. Many of the challenges can be overcome with education. Still more challenges may be overcome as demand is lowered through new technological discoveries without the use of crystal. Governments in collaboration with industry need to work together to overcome these challenges.

Works Cited

Brini, E., Fennell, C. J., Fernandez-Serra, M., Hribar-Lee, B., Lukšič, M., & Dill, K. A. (2017). How water’s properties are encoded in its molecular structure and energies. Chemical Reviews, 117(19), 12385-12414. DOI: 10.1021/acs.chemrev.7b00259

Cartier, L.E. (2010). Environmental stewardship in gemstone mining: Quo vadis? InColor, Fall/Winter(15), 12-19. https://gemstone.org/incolor/Incolor15/index.html#12

Cave’s mystery now crystal clear. (2007, July). Geographical, 79(7), 8+. https://link.gale.com/apps/doc/A166307143/GRNR?u=viva_vcu&sid=GRNR&xid=747a9c08

Elliott, H., & Bloomberg. (2020, May 29). Why people are turning to crystals and not diamonds. https://fortune.com/2020/05/31/why-people-are-turning-to-crystals-and-not-diamonds/

García-Ruiz, Juan Manuel, Villasuso, Roberto, Ayora, Carlos, Canals, Angels, & Otálora, Fermín. (2007). Formation of natural gypsum megacrystals in Naica, Mexico. Geology (Boulder), 35(4), 327.

Ho-Tin-Noé, B., Vo, S., Bayles, R., Ferrière, S., Ladjal, H.,  Toumi, S., Deschildre, C., Ollivier, V., & Michel, J. (2017). Cholesterol crystallization in human atherosclerosis is triggered in smooth muscle cells during the transition from fatty streak to fibroatheroma. The Journal of Pathology, 241(5), 671-682.

Hobson, P. (2020, January 15). What is artisanal gold and why is it booming? Retrieved from http://www.reuters.com/article/us-gold-mining-artisanal-explainer/what-is-artisanal-gold-and-why-is-it-booming-idUSKBN1ZE0YU.

Last month’s answer: Salt evaporation ponds.(Brief article). (2016). Science Scope (Washington, D.C.), 39(9), 92.

Lerner, K. L. (2014). Bowen’s Reaction Series. The Gale Encyclopedia of Science, 1, 663-665.

Lundberg, Y., Wang, X., Yinfang, T., Kevin D, & Kramer, K. L. (2015). Mechanisms of otoconia and otolith development. Developmental Dynamics, 244(3), 239-253.

McKay, D. (2020, August 27). Metals for a greener world economy. https://www.magzter.com/article/Investment/Finweek-English/Metals-For-A-Greener-World-Economy.

Merriam-Webster. (n.d.). Crystal. In Merriam-Webster.com dictionary. Retrieved from https://www.merriam-webster.com/dictionary/mineral

Nishimura, S., Ehara, S., Hasegawa, T., Matsumoto, K., Yoshikawa, J., & Shimada, K. (2016). Cholesterol crystal as a new feature of coronary vulnerable plaques: An optical coherence tomography study. Journal of Cardiology, 69(1), 253-259.

Perkins, C. (2015, June) Ten crystals with weird properties that look like magic. Earth, BBC. Retrieved from www.bbc.com/earth/story/20150623-ten-crystals-with-magic-powers#:~:text=Buried%20beneath%20the%20Sierra%20de,largest%20crystals%20on%20planet%20Earth.&text=Gargantuan%2C%20milky%20white%20beams%20of,criss%2Dcross%20the%20underground%20chamber.

Scientists reveal the hidden costs of cobalt mining in DR Congo. (2018, Oct 14). NewsRx Health, 103. Retrieved from http://proxy.library.vcu.edu/login?url=https://www-proquest-com.proxy.library.vcu.edu/docview/2116167741?accountid=14780

Sea salt vs. table salt. (n.d.). Retrieved from https://www.heart.org/en/healthy-living/healthy-eating/eat-smart/sodium/sea-salt-vs-table-salt

Shahidzadeh-Bonn, N., Desarnaud, J., Bertrand, F., Chateau, X., & Bonn, D. (2010). Damage in porous media due to salt crystallization. Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics, 81(6), 066110.

Shahidzadeh-Bonn, N., Rafaı̈, S., Bonn, D., & Wegdam, G. (2008). Salt crystallization during evaporation: Impact of interfacial properties. Langmuir, 24(16), 8599-8605.

Van Driessche, A. E. S. , García-Ruíz, J. M., Tsukamoto, K., Patiño-Lopez, L. D. & Satoh, H. (2011). Ultraslow growth rates of giant gypsum crystals. Proceedings of the National Academy of Sciences – PNAS, 108(38), 15721-15726. DOI: 10.1073/pnas.1105233108

Vekilov, P. G. (2019). Crystallization tracked atom by atom. Nature, 570(7762), 450+. https://link.gale.com/apps/doc/A591078616/GRNR?u=viva_vcu&sid=GRNR&xid=77f84e24

WebMD Medical Reference. (n.d.). Silicosis: Symptoms, causes, diagnosis, treatment, prevention. Retrieved from http://www.webmd.com/lung/what-is-silicosis.

For my term project, I visited one of Virginia’s Natural Landmarks: Luray Caverns. My experience of being so far beneath the surface surrounded by 400 million year old rock formations was humbling. I had been to Luray Caverns before, but I had never truly taken in the grandness of it all. It was surreal. I felt a deep sense of connection with the tranquil nature of the cave. The smell of the crisp, cool air, the quietness, the isolation, and the sense of being one with the Earth was awe inspiring. The tour was meditative. I felt relaxed and peaceful while admiring the beauty of the formations. The only sound was the occasional distant echo of voices from people around the cave and the faint water droplets falling from the ceiling.

My favorite part of the trip was seeing the huge stalactite that collapsed 7,000 years ago after a massive earthquake. I tried to imagine what it must’ve looked and sounded like when it broke from the ceiling. Thinking about how easily something so old and large like that could snap at any moment just reminded me of how fragile our planet is, and just how important it is to take care of our planet. Even though the earthquake wasn’t at the fault of humans, it makes me sad thinking about what has been our fault.

Global warming has been the cause of so many ruined lives and so many awful tragedies, especially in the past decade. It seems like the yearly summer California wildfires get worse and worse each year, and especially in 2020. It’s exhausting constantly fighting against the big corporations that care more about making money than human lives, and it’s starting to feel like there’s no hope fighting it.

The main root cause of all of this, I feel, is capitalism letting the American government be controlled by big corporations. Whoever has the money are the ones lobbying politicians and funding campaigns, so if a politician wants to push a more progressive policy, for example, one that might forcefully limit the amount of carbon emissions companies can emit, those companies can stop it. There’s virtually no way we can punish these big businesses for taking advantage of the system, because we as consumers rely on their products to survive.

Thinking back to Luray Caverns, I remember the tour guide constantly reminding people to not touch the formations. Some of the rocks have been rubbed away over time by human contact, and it makes me wonder if destroying these landmarks is worth being able to see them. If we thought more about the impact we have on the Earth earlier, then maybe it wouldn’t be so bad today. I’m not sure if there’s a way to help heal the planet, or if slowing global warming is the best we can do, but it brings me peace to know that even if we don’t solve global warming and the Earth slowly gets destroyed, after humans go extinct, the Earth will heal itself and life will continue on.

My Creative Work:

A Closer Look at Crystal Formation: Rock Candy

Written by Sydney Nash

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