Symmetry Operations, Types of Twinning, & Miller Indices of Crystal Planes- Mineralogy | GEO GIRL

Understanding symmetry elements and operations, twinning in minerals, and miller indices of planes is important in mineralogy and crystallography. This video covers the 4 major symmetry operations (mirrors, rotation axes, centers of symmetry or inversion, and rotoinversion axes), twinning (twin elements such as twin planes, twin axes, and twin centers, and types of twinning such as contact twins, penetrated twins, and multiple twins), and miller indices of cleavage planes (first I go over what a mineral lattice and unit cell is then a miller index, how to figure out a miller index, then we do practice!), lastly we go over the importance of miller indices (determining d-spacing with miller indices and x-ray diffraction (XRD), as well as Bragg's Law!). This lecture leads into the upcoming lectures on XRD and optical mineralogy. Reference: Chapter 5 in Earth Materials by Cornelis Klein https://amzn.to/3EEoyGI GEO GIRL Website: https://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 4 symmetry operations 0:38 mirrors and rotation axes 5:06 centers of symmetry or inversion 6:17 rotoinversion axes 7:01 twinning crystals 10:14 cleavage planes & miller indices 11:41 unit cells in crystal lattices 14:06 miller indices explained 18:15 miller indices practice 27:54 why do miller indices matter? 30:37 upcoming content! 32:31 bloopers Hey there, Earth enthusiast! Check my favorite Earth-friendly products: Bamboo toilet paper: https://shrsl.com/3cvku Bamboo paper towels: https://shrsl.com/3cvkw Compostable tableware: https://shrsl.com/3cvkz Compostable trash bags: https://shrsl.com/3cvl0 Bamboo cutlery + straw! : https://shrsl.com/3cwfl Eco-Friendly Tote (great for grocery shopping!): https://shrsl.com/3cwfp Reusable straws + cleaning brushes (my fav!): https://shrsl.com/3cwft Eco-friendly laundry detergent: https://shrsl.com/3cwgo Directly offset your carbon footprint with Wren: https://shrsl.com/3d0t2 (Just click link, press get started, take the free C footprint quiz, then choose how much you want to reduce your footprint by donating to the C sequestration projects they're funding!) Non-textbook books I recommend: Oxygen by D. Canfield: https://amzn.to/3gffbCL Brief history of Earth by A. Knoll: https://amzn.to/3w3hC1I Life on young planet by A. Knoll: https://amzn.to/2RBMpny Some assembly required by N. Shubin: https://amzn.to/3w1Ezm2 Your inner fish by N. Shubin: https://amzn.to/3cpw3Wb Oxygen by N. Lane: https://amzn.to/3z4FgwZ Alien Oceans by K. Hand: https://amzn.to/3clMx1l Life's Engines: https://amzn.to/3w1Nhke Tools I use as a geologist/teacher/student: Geology field notebook: https://amzn.to/3lb6dJf Geology rock hammer: https://amzn.to/3DZw8MA Geological compass: https://amzn.to/3hfbdLu Geological hand lens: https://amzn.to/3jXysM5 Camera: https://amzn.to/3l6fGRT Carbon-neutral pencil bag: https://shrsl.com/3cvjv Carbon-neutral backpack: https://shrsl.com/3cvkc Image sources: https://i.pinimg.com/originals/fb/18/da/fb18da62b5a2b2010d30f0315eed5b37.png http://geologycafe.com/images/forms_isometric.jpg https://webstockreview.net/images/crystal-clipart-octahedral-3.png https://files.mtstatic.com/site_4334/17576/0?Expires=1618460763&Signature=L8nc-Az8u9ZGxiOsH6wz35VxEASdW2K2WxLqUMHoSHvQxzd0KyKEUTGP43fZ2dG6v33fS-pB1kPfGGUZuEokKjyRFl8hihZvqixRcFUbI4A3WnO9foavG8FNy2MgxjWmbVntUBQ5MGdeg2bjpSBRwsm8fYKnt7Vm34FUMaXD9Fo_&Key-Pair-Id=APKAJ5Y6AV4GI7A555NA https://commons.wikimedia.org/wiki/File:Miller_Indices_Felix_Kling.png https://a.1stdibscdn.com/geometric-geology-gemstone-wooden-crystal-models-atomic-toy-building-blocks-for-sale/1121189/f_170806511575359872517/17080651_master.jpg?width=768 https://s3-us-west-2.amazonaws.com/courses-images-archive-read-only/wp-content/uploads/sites/53/2014/08/19212048/20140811155431830175.png Other figures from book: https://www.amazon.com/Earth-Materials-Introduction-Mineralogy-Petrology/dp/052114521X Disclaimer: Links included in this description might be affiliate links. If you purchase a product or service with the links that I provide I may receive a small commission, but there is no additional charge to you! Thank you for supporting my channel so I can continue to provide you with free content each week! And as always, let me know your topic suggestions in the comments down below!