Minerals
Learn about what counts as a mineral, and what crystalline structure is.
Minerals Song
A video by ParrMr. The resources accompanying this video were created by Journee Wittenberg and are shared with a CC BY-NC-SA license.
Summary
The video I chose is a fun, catchy song about minerals. More specifically it is about minerals as inorganic solids, how minerals are formed, different types of minerals, how to categorize/test them and more. It briefly touches on elements of categorizing minerals (such as the Mohs scale, streak, colour) in the bridge, but the chorus and verses focus on the things that make minerals minerals, such as the fact that they are inorganic, their composition, how they come to be made, etc.
Why Watch This Video
- Have you ever wondered what makes one mineral different from another?
- Would you like to understand the definition of a mineral and their physical characteristics?
- Have you ever been confused about the ways to test the difference between certain minerals?
Key Terms
The video I chose is a song written for American sixth graders, so this video uses words that people likely have heard and/or know about. A few terms used that I thought the majority of non-science class takers might not know about fully are “naturally occurring,” “inorganic solid” and “silicates/carbonates.”
The phrase naturally occurring when applied to objects such as minerals means they were not created by humans or not man-made. So in the case of minerals, every inorganic mineral was created from earthly processes such as magma (molten rock found inside Earth’s crust) cooling, or evaporation, rather than in a lab by scientists.
Inorganic solid (or compound) refers to any solid chemical compound that does not consist of hydrogen bonded to carbon. Any compound that consists of hydrogen-carbon bonds would be considered as organic.
Silicates and carbonates are examples of inorganic chemical compounds. Silicates are rock-forming minerals, including common minerals such as quartz, olivine, and mica, where silicon and oxygen atoms bond. Carbonate minerals are minerals made of carbonate ions (ions with carbon and oxygen). An example of a carbonate is calcium carbonate, the main “ingredient” of limestone.
Loose Ends
What is the Mohs hardness scale?
The first loose end I chose to resolve is the mention of the Mohs scale in one of the verses. It is only briefly brought up as a way to differentiate minerals, along with colour, lustre and streak testing. The Mohs scale of hardness was made by Freidrich Mohs as a way to test minerals on their general hardness by means of scratching with different material (these include fingernails, copper pennies, steel nails, etc.) Each of these materials are given a defined hardness and according to the scale, and whichever material scratches the surface of the mineral is harder than that mineral (if a mineral can be scratched by a copper penny which is a 3.5 on the scale, that mineral is lower than a 3.5).
“Found in the crust, but naturally”
The second loose end I chose was the line, “found in the crust, but naturally.” I chose this because it closely relates to one of the key terms I chose. When he says this, he is referring to the fact that all minerals are created naturally (not man-made) and can be found in the Earth’s crust in rocks and ores (natural rock in which minerals—generally metals—can be found).
How does cooling rate relate to crystal size?
The final loose end I chose was the line, “if cooling happens fast, small crystals they are had, if cooling really slow, larger ones they have.” This has to do with speed of magma cooling and temperature of magma, therefore the creation of crystallization of minerals within rocks. If the cooling down process is very slow, minerals have lots of time to grow and large crystals form. But, if cooling happens faster, there is not much time for growth, and small crystals form as a result. For example, granite typically cools slowly and therefore holds larger crystals than rhyolite, which cools quicker and usually contains crystals too small for the human eye to see.
Self-Test
Try these questions to test your understanding.
References
The Editors of Encyclopaedia Britannica. (2018, August 17). Silicate mineral. Retrieved October 12, 2020.
The Editors of Encyclopaedia Britannica. (2019, August 15). Carbonate. Retrieved October 12, 2020.
How Do Crystals Work?
A video by Graham Baird for TED-Ed. The resources accompanying this video were created by SAM Manzano and are shared with a CC BY-NC-SA license.
Summary
A way mineral crystals can be created is through a process called precipitation, where hot groundwater is pushed to the surface and cooled to form crystals under the right conditions. All crystals have a defining atomic arrangement that form repeating structural patterns, which then develop into the crystal’s signature geometric shape. A crystal’s geometric shape can vary depending on environmental conditions where they grow, such as pressure, temperature, and chemical environment.
Why Watch This Video?
- Have you ever wondered why some crystals repeatedly form specific geometric shapes?
- Would you like to know how different kinds of atoms form different crystalline structures?
- Would you like to know how the environment a crystal grows in influences the shape of a crystal?
Key Terms
Mineral. A solid that is created naturally by nature and is neither living nor made of living elements.
Crystalline structure. When the atoms in an object are arranged in an organized, repeating, 3-dimensional pattern.
Atomic arrangement. The way atoms are organized in an object. An item with a crystalline structure can have 1 of 6 different atomic arrangements.
Loose Ends
How are mineral crystals formed, and how is precipitation involved in this?
[0:28] “Heat from igneous rocks drives groundwater to the surface. As the groundwater cools, ions precipitate out as mineral crystals.”
Precipitation, for reference, is one of many possible processes that form minerals: It refers to solids being formed from gases or liquid solutions due to a chemical reaction (Panchuk, 2019, p. 100). In this video, mineral crystals were formed from cooling water, which makes this particular process precipitation from a solution.
During a chemical reaction, a soluble compound is made with a solution that it is dissolved in. This compound is called the precipitate, and when the solution evaporates the precipitate is what is left (Lewis, A. et al., 2019, p. 1301). Ionic compounds are the precipitates in this situation, so due to their chemical composition they formed crystals as the groundwater cooled.
What’s a caldera? How is it relevant to crystals?
[0:11] “Deep beneath the hot springs in Yellowstone caldera […] A magma chamber by a hot spot in the earth’s mantle…”
Calderas form when a volcano collapses in on itself, forming something like a large crater. They are usually kilometers long in width and can fill up with rainfall over time. Depending on whether or not the magma chamber is still active, magma can force its way up from the ground and come into contact with the water stored in the caldera. This can result in precipitation and depicts the situation here. (Panchuk, 2019, p. 216.)
“Given the appropriate conditions…” [1:33] What are the appropriate conditions that allow a crystal to grow?
- The elements needed to make the mineral crystal are plenty and present in that area.
- There’s enough time for the atoms to arrange into a geometric structure.
- Proper physical and chemical conditions in nature. Different kinds of crystals can form in many different ways, like through gaseous and aqueous precipitation, weathering, or under high pressures. Therefore, there’s no one condition to cover all of them; they each require different kinds of physical and chemical conditions in order to form. However, a mineral has to be naturally occurring, so they all have the similarity of being made in nature. (Panchuk, 2019, p. 100)
Self-Test
Try these questions to test your understanding.
References
Lewis, A. et al., (2019). Precipitation. Knovel.
Panchuk, K. (2019). Physical Geology: First University of Saskatchewan Edition. University of Saskatchewan.
Additional Reading
Mahan, G.D. (2020, April 2). Crystal. Encyclopædia Britannica.
McGreyne et al. (2020, February 4). Atom. Encyclopædia Britannica.
