How to Identify Metamorphic Rocks in Thin Section & Hand Sample | GEO GIRL

In Metamorphic Petrology, you need to identify metamorphic rocks and the metamorphic minerals those rocks are made of in both hand specimen and thin section. In this video, I show images of hand samples and real time video rotations of thin sections of the following:
- Marble (metamorphosed limestone) which has characteristic calcite with cleavage under the microscope
- Quartzite (metamorphosed sandstone) which is mainly quartz and I go over how to tell the difference between quartzite and marble in hand sample
- Phyllite (metamorphosed shale or claystone) dominated by foliated mica, and I go over the difference between phyllite vs schist
- Schist (metamorphosed shale or claystone) dominated by foliated mica, quartz, sometimes plagioclase feldspar, and sometimes has porphyroblasts or poikiloblasts of garnet or staurolite.
- Amphibolite (metamorphosed mafic basalt or gabbro) dominated by amphiboles like hornblende, and sometimes has minor plagioclase, quartz and/or garnet porphyro/poikiloblasts.
- Eclogite (metamorphosed basalt) dominated by garnet in a matrix of pyroxenes, can sometime have minor quartz and/or amphiboles.
- Granular, Streifen, & Augen Gneiss (metamorphosed granite) coarse grained, containing mainly quartz, feldspar, & mica.
- Serpentinite (hydrothermally metamorphosed ultramafic rock/altered olivine) containing meshy, snake-like serpentine.
- Slate (metamorphosed shale or claystone) containing illite, graphite, minor quartz and mica.
- Soapstone or Talc Schist (metamorphosed ultramafic rock) dominated by soft, scratchable talc.
References: Essentials of Igneous & Metamorphic Petrology by Ronald and Carol Frost: amzn.to/37Zs9AL
Thin Section Rotation Website: www.virtualmicroscope.org/col... (just pick a collection, pick a rock sample, and it will show you hand sample pictures, thin sections, and tell you the mineral assemblage)
Thin Section Atlas Book (in color): amzn.to/3HYsrrj
Online Metamorphic Mineral Thin section Atlas: www.earth.ox.ac.uk/~oesis/atl...
Earth Materials by Cornelis Klein and Anthony Philpotts: amzn.to/3z5sCxe
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 Marble
2:36 Quartzite
4:16 How to tell the difference between Quartzite and Marble
5:28 Real time rotation of Quartzite thin section!
7:01 Phyllite
8:31 Phyllite vs Schist
9:43 Garnet Staurolite Schist
11:23 Poikiloblasts vs Porphyroblasts
11:55 More Schist examples
14:31Real time rotation of Schist thin section!
15:53 Blueschists (Glaucophane Schist)
16:45 Real time rotation of Blueschist thin section!
18:31 Amphibolite
19:34 Real time rotation of Amphibolite thin section!
21:09 Garnet Amphibolite
22:14 Mica Schists
23:45 Eclogite
25:39 Gneiss (Granular, Streifen, & Augen)
26:48 Real time rotation of Gneiss thin section!
28:34 Poikiloblastic schists (secondary metamorphism)
30:50 Serpentinite
31:31 Greenschist
33:08 Slate
34:12 Soapstone (Talc Schist)
35:12 Upcoming videos & references!
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Non-textbook books I recommend:
Oxygen by D. Canfield: amzn.to/3gffbCL
Brief history of Earth by A. Knoll: amzn.to/3w3hC1I
Life on young planet by A. Knoll: amzn.to/2RBMpny
Some assembly required by N. Shubin: amzn.to/3w1Ezm2
Your inner fish by N. Shubin: amzn.to/3cpw3Wb
Oxygen by N. Lane: amzn.to/3z4FgwZ
Alien Oceans by K. Hand: amzn.to/3clMx1l
Life's Engines: amzn.to/3w1Nhke
Tools I use as a geologist/teacher/student:
Geology field notebook: amzn.to/3lb6dJf
Geology rock hammer: amzn.to/3DZw8MA
Geological compass: amzn.to/3hfbdLu
Geological hand lens: amzn.to/3jXysM5
Camera: amzn.to/3l6fGRT
Carbon-neutral pencil bag: shrsl.com/3cvjv
Carbon-neutral backpack: shrsl.com/3cvkc
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!

[@Smilo-the-Sabertooth]

Well my morning is off to a wonderful start, thirty-six and a half minutes of my time very well spent. Receiving the notifications every time you upload a new video always fills me with thrilling excitement. As always, It’s such a tremendous pleasure for me to be learning with someone as beautifully gifted and incredibly intelligent as you Rachel. I think your amazing my beautiful friend and I hope you’re also having a wonderful day. 😊❤😉👍

[@GEOGIRL]

Love this comment! I knew this was going to be a video that students may benefit from, but the fact that you watched it all the way through just for fun makes me so happy :) I am so glad you liked it! Hope you have a great rest of your day, friend ;)

[@Smilo-the-Sabertooth]

@@GEOGIRL Of course my friend, anything to make you happy. I always love your fascinating videos and my support for your amazing channel is still going strong because you more than deserve it. ❤😊 And thank you my friend, same to you too. ❤😉

[@cindieagle2008]

Thank you for your videos. This is what i wish i went to school for, im now 61. It has always been an interest, since i found my first piece of serpentine many (MANY)years ago. Maybe it’s not too late, but as of now I’ve been interested in petrified wood and Jadeite/Nephrite. You have helped me understand some of those processes.

[@johnnyrepine937]

Just listened to another channel's lecture on metamorphic rocks, so I'm sharing this one to Facebook and I'll watch it later, since it has such a visual component to it. 🤓

[@asmagufran5301]

I have my metamorphic and igneous prac today due to covid i could not attend those prac classes but thanks to you i believe that i will do well. Thank you for this video💞

[@GEOGIRL]

Aw, that makes me so happy! I hope you do amazing! Best of luck ;D & thanks for the sweet comment!

[@SamtheIrishexan]

This is what I thought the internet would be used for lol. I love this kind of stuff I chose finance for my degree and so without the internet would be limited to books but with stuff like this on youtube I can mix up my media. This makes rock hounding when camping something I have alot more fun doing now.

[@franciscasmith6311]

Muchas gracias !!! justamente son los videos que necesitaba para aprender sobre rocas metamorficas en el microscopio

[@USN23]

This is great!

[@schnorchzahn]

I'm loving your videos, they got me through Mineralogy and now through Petrology! For your Gneiss section at around 26 min... If you google the German word and pronunciation for "eyes" you'll see/hear how to say "Augen". 😊

[@johnnywoodstock]

Learned about poikiloblasts today. Thank you :)

[@GEOGIRL]

You're very welcome, I am got something out of it! ;D

[@ZephyrEclipse]

Great video! Exactly what I needed

[@GEOGIRL]

So glad to hear that ;D thanks for the comment!

[@armaan4287]

Thank you so much for this from South Africa! I just found your channel and this video helps me immensely as I have a metamorphic petrology practical exam tomorrow!

[@GEOGIRL]

That's great, I am so glad you find my videos helpful :D Best of luck on your exam!

[@hamarjagah6445]

also in india

[@siddhuindianclasses799]

Your every video is Very useful for me . Thank you And LOVE from INDIA ❤

[@lemiwakjira8680]

Thank you a lot

[@abeerreetsexpidition9389]

Thank you so much ma'am for teaching me paleontology

[@GEOGIRL]

Of course, glad you have found my videos helpful ;)

[@atlasl25]

Always appreciate your knowledge-rich content video and high effort put in every single video, might be you don't read my comment but I truly thank you contributed to the geology society.i am an engineering geology student in uni and sometime watch your video for revision. it always helpful.:)))), my classmate also watches this channel. hope you get more subscribers .cheers!

[@GEOGIRL]

Thanks so much for the kind comment! I am so glad that you and your classmate have found my videos to be helpful! :)

[@Jefuslives]

I was so taken aback by the beauty of thin sections under polarized light, that i forgot what the lesson was about. Probably why i went into art instead of science. 😆

[@GEOGIRL]

I know, the cross polarized light really makes them mezmerizing!😍

[@lawarlkila]

Oh my god, this is it, this is what i've been looking for. I hope it helps, although my test is from Advance Igneous Petrology 😬

[@lawarlkila]

Went thru it all, and i think i can identify some number of minerals hopefully like the Mica; Biotite & Muscovite, feldspar; plagioclase 😅, quartz, garnet, amphibole; the kinda blue-ish dots sprinkled across the thin section 😂. Thank you, thank you for this!

[@funnyperson4027]

what I am taking away from this is that literally anything can be a schist

[@ramchauhan5238]

Top class video Geo girl...👏👏👍👌.. l always love your videos..🤗

[@GEOGIRL]

Thanks so much! I am so glad you like it, I wasn't sure since it is a bit different than my normal lectures ;)

[@ramchauhan5238]

@@GEOGIRL mam.. you are always rocking..🤘🤘👌

[@princeshukla7661]

Today I am the first who's like and comment on your knowledgeable video 🤩🤩

[@GEOGIRL]

Thanks for your speedy dedication! ;D

[@evie9843]

perfect timing, i have an optical properties exam today 😩

[@GEOGIRL]

Best of luck!! You are going to do great ;D

[@ashajacob8362]

Good job nice presentation and nice video I remember studying about different types of rocks in my High School hahha 😅

[@GEOGIRL]

Wow getting into this kind of information in high school is impressive!

[@geoffgeoff143]

Very good

[@GEOGIRL]

Thanks! So glad you liked it :D

[@bertienorris44]

Singlehandedly saving my earth materials grade :))))

[@GEOGIRL]

So glad I could help ;)

[@KnowledgeHouseMrHeshamIssa]

Great work,,,,,👍👍👍 Keep moving Geo girl...👌👌👌 Your Egyptian geologist friend....⚒️⚒️

[@GEOGIRL]

Thanks so much! And how cool! I have always wanted to visit Egypt someday ;)

[@KnowledgeHouseMrHeshamIssa]

@@GEOGIRL You are welcome anytime , once you come I will be your guide not only for historical places but also beautiful and amazing geological features...

[@GEOGIRL]

Hey guys! Sorry about my moving head during latter half of the video, I must've accidentally changed a setting because it's supposed to automatically stay in the upper right corner. Also, I wish the thin section website wasn't lagging so the rotations would've been easier to follow, but you can go to the website yourself at the link in the description! ;) Lastly, to make this video, I went back into my notes from years ago when I took metamorphic petrology and I have a lot of notes & pictures from igneous petrology too, so like this comment if you would like me to make a video like this for igneous rocks! Thanks for the feedback! :D UPDATE & CORRECTION: Sorry everyone, I am working on the later metamorphic lectures now, and as I read through the book I am realizing I was wrong about the colorful grains in eclogite being epidote, they are actually most likely augite or some other kind of clinopyroxene based on how the metmorphism works in that facies. (I will explain it in my metamorphism of basalts video*) Thanks for understanding! ;)

[@Smilo-the-Sabertooth]

No worries Rachel, your video is still fantastic. And yes I think an igneous rocks video like this would be great, I’m all for it. I look forward to learning more with you.

[@everythinglegend5846]

I really enjoyed your videos, even though I don't understand most of it because am still a beginner in geology

[@GEOGIRL]

@@everythinglegend5846 I am so glad you like my videos, but I wish you understood more of them! I will try to explain things more from an intro perspective in the future ;)

[@nicholasmaude6906]

Talking about metamorphic rocks what would be the metamorphic version of Basalt and for that matter the sedimentary version?

[@GEOGIRL]

Well the metamorephic version of basalt is called metabasite (which I have a whole video about if you're interested: kzbin.info/www/bejne/hH-raGOso8aioJI). But the 'sedimentary version' of basalt (or any rock) doesn't technically exist because sedimentary rocks are just an amalgamation of sediment from all sorts of rocks (basalt, metamorphic rocks, other igneous rocks, other sedimentary rocks, etc.). Hope that makes sense ;)

[@LILLIAN559]

Thank you. You are amazing... Any study of Martian rock?

[@officeofdeath]

You rock!

[@GEOGIRL]

Thanks so much! If you liked this video, I think you'll like what I have coming out next week, another one just like this but with igneous rocks :)

[@deepakgehlot795]

HI can you explain the difference bewteen flysh and molasse facies ?

[@GEOGIRL]

Sure I can talk more about that in a future video, but until then I suggest you check out this video: kzbin.info/www/bejne/nYuadnqpfKd9Z68 at around 12:46 where I give a quick discussion about that, as well as this video kzbin.info/www/bejne/sHSum6yNgJmVatk at around 11:44. Hope that helps! ;)

[@FranciscoPereira-gc5xu]

the green mineral in the eclogite, its a piroxene (omphacite). you can probably have clorite, but the rock needs to be very retrograded

[@davejackson9819]

I sure wish you could speak at our Mineral Club members meeting. You would be a Huge hit. I will propose at least playing one of your videos on the monitor and then have one of our geologists comment on it and take questions. I’ll let you know which video we pick and how much applause you got. 😎

[@GEOGIRL]

Oh my gosh! That'd be so cool, thank you so much! I would love to hear how it goes ;)

[@burguerify]

Thanks from Mexico, If you can explain the chemographic diagramas, that would be great, it is hard for me that subject.

[@GEOGIRL]

Haha, it is hard for me too that's why I've been dragging my feet on that topic, but I will definitely try to figure it out so I can make a video ;)

[@deepakbellur9676]

Sorry, but as far as I remember of my 1973 classes, eclogite has omphacite - a variety of pyroxene. Eclogite does not have chlorite as you seem to say. Please verify. Also perhaps eclogite does not have epidote - a low temperature mineral. Eclogite forms at high temperature (please confirm). Also the term 'clasts' has been wrongly used in reference to Augen gneiss. Clasts are used in sedimentary terminology.

[@sansanernestkambire2392]

Hi Geo Girl, please, can we call rocks such as Schist, Gneiss tectonites? Please help 🙏

[@benperlstein3296]

Why didn't you describe the green/red in XPL grains in the bottom right of the Staurolite slide? I need to know what that is for an assignment :(

[@akdenizyoldas67]

Thanks a lot for your lecture.Shorter video will not be boring for us.

[@GEOGIRL]

Hahaha! Oh no, sorry if it was boring! I tried to shorten it as much as I could without taking out useful information, so maybe next time I will cut it into more than one video instead ;) Thanks for the feedback!

[@green_tuber]

In the Microphone 🤣😂 I also use it to click the pictures of samples in my practical classes 😁😁 My classmates ask me to click theirs too.

[@GEOGIRL]

Yes! It is the best way to study them without getting a headache from having to keep looking down a microscope lol!

[@abdihajji0648]

Can you please make us a video about how to Identify Sedimentary Rocks in a Thin Section

[@GEOGIRL]

Sure! What kind of sedimentary rocks? I am going to have a carbonate petrology playlist in the future that will show many thin sections of fossiliferous carbonates, but if you want other types of sedimentary rocks as well, let me know thanks! ;)

[@abdihajji0648]

@@GEOGIRL Carbonate Rocks

[@gilthunder1737]

Ily

[@adriangeology]

❤❤

[@AmanSharma-qq2gw]

ma'am can you please make more videos on metamorphic petrology?

[@GEOGIRL]

Of course, I have one coming out next week, I just had to put my metamorphic petrology course on hold for a bit since I got asked to substitute for a professor's historical geology class, so that's why there's been a lot of earth history content. But I promise I am making more on metemorphic petrology ;)

[@jakujaks9413]

@@GEOGIRL ty very much, u re teacher to me, I am really into geology recently. And I am very grateful for ur chanel. Amazing contents.

[@GEOGIRL]

@@jakujaks9413 Thank you! So glad you like my content!

[@stevenbaumann8692]

This needs to be standard training material for petrographic analysis.

[@GEOGIRL]

Haha thanks! I am glad you think so. I honestly wasn't going to post this because it isn't lecture style like my other videos and it's based on my identification skills rather than a book or paper, but then I thought about how helpful it would've been for me to have something like this when I took that class and I just decided to post it. Now it's one of my most popular videos! :D

[@4twoN8One]

Augen (eyes in German) should be ow-gen, not awe-gen. Just saying. Great video over all.

[@GEOGIRL]

Ah, thank you!

[@kidnalyounggenna9604]

U thought this the same day my lecturer did and I learnt better here lol

[@GEOGIRL]

Haha, well I am so glad you found the video helpful ;) Best of luck with your class!

[@cumberlandite56]

Nice video, but can you talk a bit slower in the next one?

[@princeshukla7661]

Hello geo girl today u looking so beautiful Love from INDIA

[@GEOGIRL]

Thank you :)

[@titusashbrook4204]

🤤 ρ尺ｏΜ𝐎ᔕᗰ