Crystal Structure, Coordination Number & Polyhedra, Pauling's Rules, Bonding- Mineralogy | GEO GIRL

This video covers how atoms and ions are arranged in mineral structures. I go over crystal structures, coordination numbers, types of coordination polyhedron (linear, trigonal, tetrahedral, octahedral, cubic, hexagonal closest packing), how Pauling's rules affect crystal structure (Pauling's rules: the electrostatic valency principle, sharing of polyhedral elements 1 & 2, and the principle of parsimony), covalent vs. ionic vs. metallic vs. van der waals bonds, and ionic substitution / solid solution. The atomic radius of cations and anions that come together to form minerals determines the overal mineral structure. This is because the size of an ion controls how many closest neighbors or neighboring ions it can bond to, aka: its coordination number. The larger the central ion, the higher the coordination number. So how are atoms arranged in minerals? Molecules can be arranged as linear, trigonal planar, square planar, tetrahedral, trigonal bipyramidal, octahedral, cubic, or closest packing polyhedra. These individual coordination polyhedra are repeated throughout the mineral structure giving the mineral a macrostructure or crysal habit dependent on its atomic structure. However, molecular coordination polyhedra can repeat in different ways, for example, silica is a tetrahedral molecule, but silica tetrahedra can be repeated and arranged in a mineral in various ways: typically as chains, sheets, or framework structures. Sheet silicates include minerals such as mica which is why mica minerals are so platy and flaky. Quartz is an example of a framework silicate structure, which is why quartz is so hard and durable. But how are these polyhedra repeated? What types of bonds hold molecules together in minerals? Types of bonds in minerals include covalent, ionic, metallic, & van der waals bonds. Salt is an example of a mineral with ionic bonds, diamond is an example of a mineral with covalent bonds, gold is an example of a mineral with metallic bonds, and graphite is an example of a mineral with van der waals forces. However, minerals can contain multiple types of bonds, for example, ice contains both covalent bonds and hydrogen bonds, which are van der waals bonds. Lastly, I discuss substitution of ions into mineral structures by replacement or insertion into interstitial sites or vacancy sites between ions. Hope you enjoy! ;)
Reference: Chapter 4 in Earth Materials by Cornelis Klein: amzn.to/3mnQqcb
GEO GIRL Website: www.geogirlscience.com/ (visit my website to see all my courses, shop merch, learn more about me, and donate to support the channel if you'd like!)
0:00 Common ions in minerals
2:20 how ion size affects mineral structure
4:43 Atomic arrangements (coordination polyhedra)
8:49 Coordination number & polyhedra practice!
9:43 Silicate structures
11:15 Paulings rules
11:51 The coordination principle
13:45 The electrostatic valency principle
16:13 Sharing polyhedral elements I
17:01 Sharing polyhedral elements II
18:14 The principle of parsimony
19:05 Forces that hold crystals together
21:44 Chemical bond types
24:32 Atomic substitution or solid solution
28:21 Upcoming content!
29:04 Bloopers!
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[@alanbelasco2931]

Magnetite is my favorite mineral because it's used by female sea turtles (and some other species) to help navigate the open ocean using Earth's magnetic field to return totheir natal beach to lay eggs some 20 to 30 years after they hatched. Question: The substitution of strontium for calcium in calcite shells in a cold-water environment is very interesting. Can, or do, scientists measure strontium amounts in fossils as a proxy for describing paleo marine environments or as evidence for the environment in which a species lived? I'm a retired paralegal, not a scientist. Thank you for your hard work and excellent presentation.

[@barbaradurfee645]

So interesting ❤

[@marcosjimenez616]

Just started my mineralogy class! This helps a lot get a insight of what is to come! Please continue to post when you can!!! *subscribed* Thank you

[@GEOGIRL]

So glad to hear that! Thank you for subscribing :D

[@barbaradurfee645]

Making Paulings rules fun-you rock!!

[@mistressofstones]

I never got a chance to study science at this level in high school because I was obsessed with the humanities and the arts at that time, and its where my natural talents lie. BUT I started collecting minerals during the pandemic and its brought me to a place of suddenly being interested in stretching my mind past my comfort zone to understand how these beautiful crystals are formed and what they are made of. Thanks for making this information easily accessible for me.

[@anarcho-geologist4528]

Very well done video! It’s nice to see more geology content on KZbin! I look forward to more of your work!

[@GEOGIRL]

Thanks! I am so glad you found it helpful! ;D

[@alanbelasco2931]

Never mind. I just watched the lecture on Strontium isotopic behavior and proxies. Thank you.

[@JC3Nipp]

Thank you for these videos! It helps to have some review for my classes!

[@GEOGIRL]

Thanks for the comment! So glad my videos have helped you :D

[@atb3569]

it is really helpful and easy to understand. Thank you for your lectures

[@lethargogpeterson4083]

This video clarified some stuff from a geology textbook someone loaned me, and even taught me stuff I don't even remember. Well done explanations. Thank you.

[@GEOGIRL]

Thanks for the comment, I am so glad you found it helpful ;D

[@conorhaynes-mannering5094]

I'm doing an Environmental Science Course and your videos are tremendous help! You cover things amazingly and also have a really accessible video/presentation style, I have no idea why you aren't rolling in tens of thousands of subscribers yet! You will be soon! best educational geo content on KZbin!

[@GEOGIRL]

Wow, thank you so much! This comment is so sweet, the "best geo content on youtube" part just made my week! And I am so glad you have found my videos helpful ;)

[@conorhaynes-mannering5094]

@@GEOGIRL Honestly I didn't think I could find anything this good for learning geoscience all in one place, definitely recommend to everyone on my course!

[@GEOGIRL]

@@conorhaynes-mannering5094 Thank you so so much! I hope you all find it helpful :D If you or any of your classmates want to request any specific topics for future videos, just let me know ;)

[@conorhaynes-mannering5094]

@@GEOGIRL Brilliant! Will do!!

[@JoesFirewoodVideos]

This should be a interesting video. TGISu. Thank God It’s Sunday, the day GEO GIRL posts new content. I ❤️ GEO GIRL

[@GEOGIRL]

Yes haha I love that TGIS!

[@wonderfulscience427]

Really interesting topic. I was wondering whether you could do a video explaining crystal nucleation in the melt and also precipitation of crystals from aqueous solutions and the underlying thermodynamic aspects. It would be really appreciated.

[@varshadoss5431]

Great work

[@GEOGIRL]

Thanks so much ;)

[@cosqunqasimov8344]

thanks a lot it is very helpful

[@jimmylalnunmawia8738]

Its pretty concise, I like it!

[@GEOGIRL]

Thanks! I am glad you thought so, concise is what I aim for but sometimes I miss the mark haha! :)

[@pauljackson3491]

For the quantum numbers, I was thinking that n could be like the size of the orbital, l could be the elongness, is that a word, n=5 and l=0 is a sphere while l=2 stretches into a dumbell, etc. The m quantum # is the direction, that's why they can be equations like x or xy. Diamond and quartz, and even ice are strong possibly because they are all tetrahedral. Maybe that is the strongest bonds between atoms. I heard an interesting theory for van der waals bonds. It's like the electron sloshing around in the atom. At some point the electron is on 1 side creating an attraction.

[@GEOGIRL]

Yea, thanks for clarifying that about the quantum numbers! Also, that's awesome I never put it together that the strong minerals tend to be tetrahedral, great observation. Also, you are completely right about van der waals forces, the electron density being more one side of the atom than the other creates a dipole! The dipoles then cause attraction between molecules!

[@brahimbest1]

As always awesome and informative video from GEO GIRL❤ My favorite mineral is the black opal CN=coordination # =closet neighbors ,[now I'll never forget this abbreviation]

[@GEOGIRL]

Haha I know the double meaning of CN really made me happy when I realized it ;D Also, thanks for sharing, I just went down an image rabbit hole of black opal and I am now obsessed!

[@robertturner1308]

“Size matters” made me laugh.

[@GEOGIRL]

Hahaha, I'm glad you enjoyed my accidental joke lol ;)

[@shubham_nigam]

impeccable and very helpful video. Thank you so much! subscribed to the channel. Looking forward to other videos. :)

[@GEOGIRL]

Thanks so much for the comment and for subscribing, I am so glad you found the video helpful! I hope the rest of the videos on my channel will also be helpful to you ;)

[@p_er_man]

Turquoise 🔷

[@thebumblecrag61]

A fantastic video

[@GEOGIRL]

Thank you! ;)

[@avikmanna3394]

Thank you so much, your video helped me a lot😊😊

[@GEOGIRL]

You're welcome so much! Glad it helped you out ;D

[@lakeshmasulkar9166]

thanks,very informative

[@GEOGIRL]

No problem, glad I could help! :)

[@ericclayton6287]

Personally, I am aghast at the variability of calcite forms and love the zeolite group.

[@GEOGIRL]

Yes! Calcite is too cool! :D

[@mi4208]

My favourite mineral is tourmaline and Galena I know it is poisonous but I like that shinning surface

[@GEOGIRL]

I love tourmaline and galena too! Tourmaline can take on so many awesome colors and galena is so cool to me because you look at it and think it won't be that heavy, but then it is!

[@youngderro1007]

Size matters😃. Great video though, thanks.

[@shelelekindnew6296]

very helpfull thak you

[@GEOGIRL]

Of course, you are very welcome ;) So glad you fnd it helpful!

[@johnscovill4783]

Icelandic spar. Wow!

[@haileyb.7620]

technically a mineraloid, but I've always found obsidian so beautiful with its color and conchoidal fracture 🥰

[@sourabhhanje6724]

You are awesome :)

[@GEOGIRL]

Thank you! ;D You are too!!

[@CaptainMir]

Nice 👍 video

[@GEOGIRL]

Thanks, glad you liked it!

[@Mathilde_Moksha_333]

Hello :) I don't have a favourite mineral yet, though it surprises me how I didn't connect geometry and minerals together before ! Thank you 😄 Well, now that I think of it, is graphene considered a mineral ? I think it's made of many sheets of graphite, and its possible use as battery material would make it my favorite if indeed it is a mineral 😁

[@GEOGIRL]

YES graphene is to my understanding a single layer of graphite (so basically a single sheet of carbon atoms, SO COOL), and if I remember correctly, it is also stronger than diamond! What a great choice! ;D

[@mi4208]

Can you suggest any field related skill that I can learn in lockdown and will help me after lockdown in geology field study

[@GEOGIRL]

Good question, I guess it depends on what area of geology you will be going into. If you lean toward more geophysics/structural geology I would say being able to interpret strike/dip and those types of features is very helpful. But in general, I think my most useful field skill has been interpreting lithologies and depositional environments of rock formations (so stratigraphy). That's a great one to master. Best of luck! :D

[@mi4208]

@@GEOGIRL Yeah thanks for your precious time and reply I have asked same question they said that I should focus more on GIS and learn any programming language like python or JavaScript

[@GEOGIRL]

@@mi4208 Yes, GIS and coding is very important as well! I don't know if I would call it a 'field' skill, but it is certainly a very useful geological/technical skill to have :)

[@JoesFirewoodVideos]

Is quartz considered a mineral?

[@GEOGIRL]

Yep, quartz is a mineral! :)

[@grahamhagerty8648]

Olivine

[@Be_Harris]

You have words that hurt my brain. 😐

[@johnscovill4783]

It’s called octahedral because there are eight faces in an octahedron

[@gangrebe7228]

Intelligence is close to godliness

[@nishantchoudhary4168]

size matters...😂

[@KerriEverlasting]

Why does it make my stomach into knots? 😨🤦‍♀️😭

[@KerriEverlasting]

Listening seems less horror inducing than watching... let's give that a go a few hundred times before I peek a look.