33. How to Identify Rocks

[Music] [Music] what is a rock you might think this is an easy question to answer but rock is both a common word and a scientific term and sometimes this causes confusion over whether or not something should be called a rock in geology a rock is solid naturally occurring and made of minerals or mineraloid matter so this means to understand what a rock is first we have to explore minerals i'm science mom i'm math dad today we're going to show you some simple tools that you can use to identify rocks [Music] welcome today we're going to be learning how to identify rocks but first like we said we're going to dive into minerals and give a quick welcome to some of our viewers watching live hello to kendall from illinois elise from the uk and mariah watching in california shyla from texas cassidy from mississippi xander and amelia from alabama we're happy to have you with us and a special welcome to you if you're watching the replay i'm pretty excited for this because i'm not very good at recognizing rocks i think i can usually tell what is a rock although that can actually be a little more complicated as well there are a couple important tools that will help you identifying rocks one is to recognize how hard the rock is we'll talk about mineral hardness in a minute the other is to be able to look closely and a magnifying glass can help and see are there visible crystals are there layers those three things or clues that can really help you identify a rock and then the fourth one which is also very important is where did the rock come from because location can be really helpful but before we dive into those processes let's talk about quartz one of my favorite minerals of of all so quartz is a pretty common one right it is and i have a sample of quartz right here two of them and you can see that it has a really pretty crystal structure parts of it are even a little bit translucent and it was not carved like this this quartz crystal grew into this shape all on its own because it is a crystal whoa it looks like glass it's so clear almost no way so that's naturally occurring this is naturally occurring this is natural quartz and it grew like this now a crystal is something that has a regular repeating pattern and there's a really common crystal probably in your fridge right now it's called ice oh because when you're in a freezer for sure in your freezer that's what i meant it because water when it freezes it likes to lock into a pattern into a crystal pattern and quartz which is made out of silicon and oxygen quartz does the same thing so like in a cave or how does that we're underground underground underground so yeah it forms underground as um as igneous rocks are cooling down really slowly you will get quartz forming now this is quartz but this is also quartz this is smoky quartz if you can zoom us out just a tiny bit math dad so they can see that just a little bit better look how cool these crystals are they're all growing up and again this is naturally forming but the color is completely different so color of a rock turns out to not be the most useful thing in determining what a rock is because this is quartz this is quartz and this is quartz 2. now it's a little hard to see with our light here but this is actually yellow and if this is polished and cut to be a gemstone then it looks like this this is citrine raw citrine and then polished and cut citrine it is also quartz it's a yellow variety of quartz no way this one looks like a gemstone it is in a ring yes yeah those are all quartz these are all that makes almost no sense so what is causing the difference in the colors tiny amounts of other elements or other atoms so quartz is mostly made of silicon and oxygen silicon oxide but there are two other little elements that can get in there and just a little bit of a certain element can cause a huge difference in color and we see this especially with corundum have you ever heard of corundum math dad i have that's a pretty hard one right it is a pretty hard it is a gemstone a mineral and depending on which variety you have it will be different colors and it could be do you remember the two it's a ruby it could be a ruby if it's red or sapphire or a sapphire if it's blue and then there are colors that are sort of in between that spectrum as well but they're the same thing they're both corundum so just other impurities or other elements are somehow in there and that's where we get the difference in color that is where we get the difference in color let's talk just a little bit about gemstones because when some people hear mineral they think oh like diamond and quartz so we're just talking about things that we would put in in you know someone's crown right we're just talking about jewelry well no we're not just talking about jewelry but gemstones are and are very valuable to us human beings because they are so hard and beautiful and you can cut them into these expensive and gorgeous shapes and so we like gemstones as as a species but there are a lot of variety with our gemstones let's take a look at some some cool examples so this is not necessarily a gemstone it's a rock it's called tiger's eye and it's usually polished to look like this and i i brought this just as an example to see how different something can look when it's raw versus polished because here is tiger's eye before being polished okay so what does one do to polish a rock you've got to tumble it so people will have rock tumblers which basically is just a big barrel with some rough stuff in it like sand and you just tumble it around and around and around kind of like what would happen naturally in a river okay so that kind of breaks off any corners and it smooths the edges out but but how does it make it shiny did the tumbler make it shiny yeah just getting it smooth so this this surface here if we polish it and get it really smooth it would also look similar but this has been cut but not polished as smooth as this one has so these are all tiger's eye this is raw tiger's eye that hasn't been tumbled or polished yet this one has been cut but not polished and then here is one more example this is aquamarine another gemstone this is raw so it's a slightly bluish cast to it is that where the name aquamarine and this one is polished and if it was cut to look like a gemstone then it would look sort of like a bluish diamond only this is not as hard as a diamond well that's way cool i mean i i couldn't recognize a diamond even if i had a magnifying glass i wouldn't know what to look for although professionals do know what professionals do and then this right here this is opal common opal you can see it has a beautiful color and if we were to polish it and cut it a little bit more nicely this could be this is used as a gemstone as well but this is not a mineral wait what's a mineral then because remember a mineral is something that has a regular crystal structure where the atoms are stacked and arranged in a really organized way and if the atoms are not arranged in an organized way if they're just kind of you know all over the place then it is not a mineral and we can call it a mineraloid like it's similar to a mineral an obsidian is a great example obsidian is volcanic glass it's an igneous rock cooled down really quickly the atoms here because it cooled down so quickly they did not have time to organize themselves and get all into a crystal structure and so this is what we call amorphous that means the atoms are not lined up so this is obsidian if we were to cut it and maybe make it look like some sort of a black gemstone it would not be a mineral it's a mineraloid mineraloid and there are several things that are not minerals that we call precious gems let's take a look at our notes real quick we're going to be on page 81 and i have a little venn diagram to help kind of separate it out what's a mineral what's a mineraloid and what is a precious gem or a gemstone because they're not all the same thing so we'll come to back to this one in just a minute here we are on page 81 all right now an opal the stems the stones that we were just looking at these are gemstones they're often used in jewelry but they are not minerals they don't have a crystal structure pearls come from oysters they're actually made by a living thing and they are beautiful but they're not a rock they're not even a mineral because they are made by a living organism oh and that's part of that definition yes same thing with amber so amber is fossilized tree sap it looks really beautiful and sometimes can be used as a gemstone but it is not a mineral and not a mineraloid either it's kind of a separate thing interesting and then coal can actually be cut and into a gemstone if it's hard enough and that's called jet so here is a piece of coal this is actually um a hard enough piece of cold if we wanted to polish this we could and it would be a gemstone called jet jet okay that's a cool name for a gemstone it is i think we can all agree on that oh no i'm sorry we hold up the coal again we were in the small picture mode there we go that is a piece of coal crazy so is coal a mineral math dad don't look at the flow chart oh man no hints from the chat so it's yeah absolutely yeah it doesn't have a crystalline structure so yeah it's the mineral it is not minerals it does not have a crystal structure oh it doesn't have the crystal strength it doesn't have a crystal structure are you gonna find coal with little crystals of coal growing out no because it is not a mineral all of the atoms are kind of smooshed in and they are not organized but there are lots of different types of minerals and one of my favorites is called selenite take a look at this this is sometimes called desert rose shout out to ibrahim from canada who identified that correctly from the thumbnail and it is naturally forming it forms like this all on its own and these little ribs that come out that are dusted white that happens because it is a mineral and those atoms want to line up in an organized way they want to be all lined up and this forms naturally just like those quartz crystals did that's that's neat i saw that the chat everybody was getting the question right that i got wrong so coal is not a mineral i'm gonna remember that one from now on good job unbeatable science kids i want to show another example that color is not a very good thing to use when you're identifying rocks and that's because this and this are both feldspar what feldspar is one of the most common minerals on our planet a lot of rocks have feldspar in them and it's it's not a mineral that you're going to see growing into crystals like you do quartz where they're a really pretty glassy structure but if you look under a microscope and you look at the structure there is organized and organized lattice to this to this mineral and certain types of feldspar will actually form layers this is labradite feldspar isn't that beautiful yeah it is but you don't see it unless you polish it without being polished it looks like it looks like this you can kind of see that there's some striping there but it's not nearly as obvious and this makes me want to polish some rocks yeah gotta get a rock tumbler but both of these are feldspar do they look the same not at all i would never guess that those were the same minerals very very different appearances and they're different a lot of different varieties of feldspar but if you look at what the atoms are and what they're made of and how the crystal forms they're pretty similar even though they have totally different colors okay next way cool there's one more mineral i want to talk about that you actually have in your kitchen right now you're talking about our granite countertop nope nope not the granite countertop although the granite countertop might have some quartz crystals in it but granite itself isn't a mineral i'm talking about a mineral that you eat and if you're watching the replay see if you can guess the answer before math dab a mineral that you eat that is in your kitchen that can form a rock okay i got i've got a theory it's got to be the milk i think the calcium the calcium amy's got it dexterous got it rachel's got it what oh it's salt this is halite or rock salt and we call it rock salt because it literally does form rocks so this forms on the top of a lake bed and when they went and harvested it it looked like this and you would reach underneath and then break it up and when you turn it over you see these incredible crystals those are huge they are huge and they have a square shape because salt forms a cubic crystal they meet at right angles yeah it really is isn't like a pointy diamond no so math dad is this a rock well it's a are minerals rocks because i i yes it's got to be a rock it's natural it's got a little crystal it's formation and yeah it's it's a rock yes it all depends on how you define rock and sometimes people will get in arguments even fellow geologists can get in big arguments about whether or not something is a rock but if we define a rock as being naturally occurring that means it's not man-made or animal made and that it is made of minerals or mineraloid matter and that it is solid then this is a rock and it's made of salt but this rock here if you dropped it in a bunch of water it would eventually dissolve because it's it's made of salt it is rock salt it's kind of weird to think of a rock dissolving and if this rock is put under a lot of pressure there are certain rock salt deposits that would not dissolve very easily because they are so compacted but this one was formed on the top of a lake and it would dissolve so that's why we're not getting it wet so something like a brick is not a rock because it was man-made that's right if an animal helped to create it then we don't call it a rock because rocks are naturally occurring out in the natural world without some animal making them we cool now we are ready i think math dad to try identifying our rock okay i have a rock right here and we are going to go through our little flow chart and see if we can figure out what this rock is oh so this is the flow chart in the notes on page 82 which you refer that is right and this first question on our flow chart has to do with where you are and when you're identifying rocks and trying to figure out what a rock is the best question to ask first is where did the rock come from because there are geographic not geographic geologic maps that will show you what type of rocks occur where and that can be really helpful as you try and figure it out so first question is the rock soft enough to flatten with two fingers this is a fairly important one because sometimes you'll pick up what you think looks like a cool rock but it actually might be something like deer poop and if it's squishy then go wash your hands because that was not a rock all right so the answer is no in this case so we're looking at this particular rock all right so look at that two for one are we in hawaii did this rock come from hawaii no if it did come from a hawaii then most likely it was basalt yeah okay so no we head down here if you drop vinegar on the rock does it fizz and let's go let's go back to our main view i did so when i say fizz i don't mean like fizz like erupt in bubbles like dropping mentos into soda but if you drop a little bit of vinegar on a rock and especially if you kind of scratch the rock first if you see little bubbles coming up that means the rock is made out of calcium carbonate calcium carbonate is one of the minerals in that rock most likely it's limestone or marble but sometimes you have sedimentary rocks that are cemented together with calcium carbonate so rock identification can be a mystery it can be a puzzle is calcium carbonate like baking soda it's it's very similar to baking soda yes now this rock here it does not fizz so we're going to go to our next branch in our little trail all right so you said the answer was no so we're following it along this way does the rock have layers does the rock have layers and this one can be a little bit tricky to answer when i look at this rock i do not see layers so but you know what if i look at it sideways i do see some layers do you see that stripe of black and then there's a stripe of ground so at first if i look at the top i'm going to say no layers but then if i look sideways say wait a second there are some layers so let's say yes all right it does have layers all right so we are right here wait wait oh does there oh i'm sorry did i jump down too far all right so yes all right we're headed over to here does the rock have crystals i'm sorry or large parts large particles so are there crystals on that rock this is another question that can be kind of tricky to answer let's go up to our big view just real quick and talk about why would we care about crystals and it's because if the rock has crystals that are visible that really helps us to identify if it's a sedimentary rock or a metamorphic rock because crystals form when you have a rock cooling down very slowly or with a metamorphic rock sometimes if the rock gets hot enough pressure you can get crystals forming but sedimentary rocks sedimentary rocks you're gonna see grains you're not gonna see you're not gonna see crystals so for this step you actually need a pretty good magnifying glass or a little pocket telescope to look and see are there crystals and on this particular rock here i could see just some really really fine crystals so the answer is yes all right so does it have crystals so the answer was yes and it turns out this is a piece of nice spelled g-n-e-i-s-s it's a nice rock i like it nice is a metamorphic rock and that's kind of where it gets its crystals from this is actually granite nice it was a piece of granite that was then pushed deeper underground and reheated again and kind of kind of moved so nice nice a nice rock that's pretty cool so i mean this flow chart isn't comprehensive it's not going to be perfect but it's going to give us it will give you some good ideas it will give you some good ideas so when you get a rock you can just follow that flow chart from one answer one question to the next and hopefully you'll be able to identify what rock you have i want to talk a little bit more about mineral hardness because i have here a piece of chalk and we had a couple good questions in the in the chat where people were actually asking is chalk a mineral and it is this green sidewalk chalk that i have right here i would not call um a naturally occurring mineral because it was obviously produced and made you know by people but there are natural chalk deposits where this is really this is the mineral talc that's what this is oh calc is that the softest of all the softest of all the minerals so if i take this piece of chalk and i scratch it along my piece of nice what's going to happen the nice is going to not get dirty but this will actually rub off this will rub off the chalk it's right so i just made a streak of chalk across my nice rock what if i do the reverse i have my piece of chalk here what if i scratch the nice what if i scratch this rock on the chalk well once the same thing roughly will happen well it's going to make it's going to make a scratch see so did i get pieces of my rock that rubbed off onto the chalk no i made a scratch but if i take this i make a streak that means that pieces of this rock because it's softer have actually rubbed off onto my rock and this is exactly how the mineral hardness scale works there was a scientist way back when who made the mohs mineral hardness scale and he took lots of different minerals and he said you know what we can really tell a lot about these minerals just based on how hard or soft they are so quartz on the mohs hardness scale has a hardness of seven talc the softest has a hardness of one and our finger nope and a streak plate is super useful in telling where you are on that scale if you take a piece of porcelain you can even take the bottom of a porcelain bowl if you have a porcelain bowl at home use that as a street plate if the rock leaves a streak then it is less than seven in hardness if it scratches your porcelain then it's higher than seven well that's pretty cool that's a really good guide right there so let's take a look at the whole mohs hardness scale give diamond is at the very top that is the hardest mineral of all and we think diamonds are valuable because they we have a tradition of putting them in jewelry but really the most valuable use for a diamond is cutting things in industry with machine shops and all sorts of production lines diamond drills are used to cut things because they are the hardest thing we have to cut with pretty much that makes a lot of sense yeah and your fingernail actually has a hardness of about two which means that your fingernail is hard enough to scratch certain types of rock like the talc like the talc and why cook gypsum so i have a piece of gypsum here and this piece of gypsum actually came from near lake mead which is right next to where i live it is a mineral it has a clear crystal structure and its crystal structure is so ordered you can actually see through it whoa isn't that amazing so it's so ordered so then they're lined up in such a way that the light can pass yes the atoms are lined up so nicely that light can just pass right through and this plate right here if i just take my fingernail my fingernails aren't too long but they're long enough if i push down i can scratch don't do it i can scratch the surface of this because it is so soft and don't worry about that we can we can polish that off later if we want to all right all right he said this one was called what this is gypsum oh that's gypsum well that's interesting because when i think of gypsum i usually think of that sheetrock so in most people have walls that with sheetrock behind the paint and that sheetrock is made of gypsum and it's it's made of material just like this so gypsum occurs naturally out in nature it is deposited and we go and we harvest it and mine it and then grind it up and use it to make sheetrock so that's probably the strongest thing that our nails can scratch on that mohs hardness yes yes all the other rocks if you try and scratch them with your fingernails you'll end up filing your fingernails instead you'll leave you'll leave a little streak of fingernail on the rock because the rock is stronger so a streak plate is super useful in telling how hard a mineral is and then of course looking to see are there crystals now let's let's go look back i want to talk about four minerals and then we'll have our where in the world question and we'll go to our questions for you guys so if we can go back to the notes real fast okay oh do you want to say that i just wanted to take take another look at this because i think this is so cool so yeah got talc gypsum calcite fluorite appetite orthoclase i've never heard of that quartz topaz coronado that's the emerald and ruby yeah yeah and then diamond ruby sorry i said that wrong oh yes yeah it makes me wonder where emeralds or other gemstones fall in here things like pearls but um yeah so steel nails fall in here somewhere a glass plate somewhere between a five and a six a copper penny somewhere between a three and a four so a copper penny is actually somewhat soft compared to the other items on this list yeah i usually think of coins as really strong but all depends on all depends on the coin all right let's pull up the notes we're going to just come down here real quick on this page 81 because sometimes we think of rocks as just being in neat categories like that all rocks are either sedimentary metamorphic or igneous but some rocks kind of fall in between so coal is a sedimentary rock made by you know ancient plant material that got squashed down to a layer but if that coal is heated enough that it really becomes compact you could argue that it's a little bit in between sedimentary and metamorphic not every rock fits into each category and this rock that i have right here this is a small rock but math dad i want you to hold it real fast that's kind of heavy it's really heavy and then let's let's look at this close view so i can show this one off this is an iron nickel meteorite a small piece of a meteorite and it has so much iron in it it feels way heavier than any natural rock and a meteorite is that a sedimentary metamorphic or igneous rock well it all depends you could actually make an argument that it's any one of those depending on where it came from and what type of meteorite it was wait what about moon rocks moon rocks are all going to be igneous pretty much there we don't have the sedimentary you know you don't have sediment on the moon that is cycling in layers and compacting you don't have water moving through to cement sedimentary rocks together and you don't have plate tectonics to heat up metamorphic rocks so all the rocks on the moon are igneous but they've been cooled down for a long long time let's look at four minerals real fast and then we are going to get back to our where the world mystery and our questions all right so this hard minerals found in igneous rocks like granite it's a main ingredient of sand and when purple it's called amethyst that's just going to be straight down to quartz right that is quartz and adeline asks why is quartz so common it is one of the most common minerals and it's because it is so resistant to erosion it just stays around because it's so hard it's a seven on the hardness scale which actually means it's a hundred times harder than talc is right all right these minerals are the most common on earth's surface they come in three main varieties potassium sodium and calcium used in making ceramics and glass and i have a hint right here oh these two varieties that i showed earlier this is yes feldspar is actually the most common mineral on earth there are so many different varieties of feldspar and like you saw from looking at these two the labrador and the other one it can look really different depending on what it is that's that's really interesting i'm curious let me know in the chat have you even heard of feldspar before that's that's not a very commonly used term as far as i know all right up next this mineral will dissolve if placed in vinegar okay so that was calcite that is calcite and then last but not least we have the mineral that i scratched and that your sheetrock is made out of so soft you can scratch it with your fingernail that's right gypsum and last little one i want to show you this is mica and it has such such dramatic layers that flake off so easily there was a mica mine in nevada that was located several hours drive from here and in the early 1930s at this mica mind people made windows out of mica they would take a large piece of mica and they would carefully peel off one of these pieces and if they got it small enough it was translucent light would pass through and that's what the miners used to make windows in their in their homes whoa kind of crazy right yeah it is so there are so many different cool types of minerals from mica which comes in sheets to selenite which has this beautiful rose-like pattern to pyrite also known as fool's gold and on and on i hope this just gives you kind of a fun taste for how how much variety there is with rocks and that you enjoy exploring and learning more about them and one last little example calcite has so much variety this is a piece of banded calcite that our friend who's a geologist lent to me isn't that beautiful oh yeah it's gorgeous but not this is kind of a rare specimen most calcite looks completely different from this and the little drawing that i showed we saw that sometimes it can be kind of cube-shaped sometimes it can form beautiful little structures calcite has a lot of variety all right ooh one question for you science mom before we even get to the poll questions there was one type of mineral that gets used in baby powder or at least was at one point talc that's right i do i do talcum powder yep all right you ready for the wear and the world mystery map dad oh yeah this one this one's a tough one i don't think you're gonna get it okay imagine sweeping white sand dunes but this isn't a desert these dunes transform into blue lagoons during seasonal monsoons do you have any idea the goons let's see them monsoons okay so it's somewhere sweeping dunes so somewhere extra sandy but it's not a desert it's not a desert not a desert have to be a beach since you're talking about blue lagoon so that makes sense is it right behind me it is not right behind you so this is a national park in brazil called um and it's a little difficult to pronounce i wrote myself a tip lancois marines national park okay i have never heard of that that is beautiful and the reason why it looks so amazing is because there are sand dunes and then underneath that layer of sand you have igneous rock that is not permeable that means the water can't go through it and so when it rains the rain goes and kind of hits those sand dunes and then just stays there and it takes a while before it either soaks into the sand or evaporates or slowly runs to the ocean and it doesn't get very much rain just once a year they'll get these monsoon rains that dump a lot of water and then the rest of the year it's dry a really cool environment and caused in large part by the geology by the sand and then underneath a layer of rock that is not permeable yeah i don't know i don't even remember seeing pictures of that before but that was really neat yeah you throw it one more time yes i'll grab it one more time there it is lanswell moraine's national park it is in brazil up near the sort of the top of brazil nice and now you're ready for poll questions go to itempool.com sciencemom live or if you're watching the replay at science.mom you can click right below the thumbnail and it will bring up the poll questions all right we have some birthday shout outs today we do have some birthday shout outs a very happy birthday to katya who turns 12 today happy birthday katya and a happy birthday to amriah tomorrow woohoo and lila from colorado turns 10 today happy birthday lyla or leela i'm not quite sure how to say your name but happy birthday all right was i looking at the wrong camera math dad right right whoops wait we're here so as a birthday present i'm gonna crush you guys that's what math dad thinks but i don't think so all right first question what is the hardest mineral in mohs hardness scale and i totally spelled mo wrong didn't they m-o-h o-o-m-o-h-s okay math dab the unbeatable science kids are very forgiving because they they win every time all right and i didn't mean i would crush you on this question i know you're gonna get this one right most of you but what is the hardest mineral and when we say it's the hardest the most mineral scale it doesn't go like a two is twice you know is a little bit harder than a one and a three is a little bit harder than two each time it just about doubles oh wow so the hardest mineral is actually 1 500 times as hard as the softest that's pretty cool all right and the answer is diamond all right nicely done many people on that one all right gotta build you up before i crush you question two which of these is not a mineral so select all that apply we've got emerald garnet opal sapphire obsidian salt select any of those that are not minerals and don't select the ones that are minerals as we were taught earlier i just saw my notes from the moderators we also have a birthday to natalia happy birthday today creative koala great lots of birthdays all right i'm seeing three categories get a lot of votes one one's in the lead i'm not sure interesting hmm so we have maybe are they all minerals emeralds garnets opal sapphire obsidian most sand that we see is made out of quartz but i actually have here a sample of sand that is made out of garnets oh sorry all right i'm doing this oh you want me to show that yeah real fast so this sand oops i put it too far this sand is from near washington and oregon a geologist friend of mine collected it and all of that each of that is garnet but and garnet is a precious gem but these pieces are so small you couldn't cut them into a gemstone no isn't that neat though that that is neat and it looks kind of purple all right and so the answers were obsidian and opal okay so there were several depict other things so emeralds are minerals garlics or minerals sapphires are minerals and salt i am so happy to see that salt didn't get as many as many votes because you guys were listening salt is a mineral that's right okay so i didn't stump them that time although i did get several people to pick incorrect answers question three which mineral will dissolve if placed in vinegar calcite mica quartz feldspar one of these will definitely dissolve and the others will not [Music] oh man isaac had a great question about our rock salt why is it pink and i believe it is but i would have to double check this to be 100 sure i believe it's because there are trace amounts of iron in the lake and i think that's what gives it its pink color and some halite is pink and some halite is not you'll find this in in different colors depending on where it's formed cool all right the answer is calcite well done well done okay which two gemstones are made of the same mineral so in particular of the options listed below two of them are made from the same mineral i want you to select those two and don't select any others only pick two another great question from pickle obsessed can you make rocks at home with salt you can definitely make salt crystals at home just by making a salt solution and then putting a string or something that the mineral can form in and letting the water evaporate and salt crystals will form and they will have the similar cubic structure as they form getting them to grow as big as this though is challenging the biggest salt crystal i've ever grown at home was about that big and i was so proud of myself we'll put it on your tombstone sam one screw a salt crystal that big it was about the size of a large pea all right and chessa's ruby and sapphire i think that's that's so cool that rubies and sapphires are made from the the same mineral they are they're called corundum and corundum is next down from diamond corundum is very hard on that mineral hardness so these precious gemstones are typically going to be pretty high on that scale yeah all right question five a rock with layers is most likely to be sedimentary metamorphic or igneous which will it be isabelle had a really great question can any rock be a gemstone like how does a rock become a gemstone and this reminds me of the question what's the difference between a weed and a flower and it really all depends on like well what do you want in your garden if you have a garden and you're growing carrots and then you have geraniums get into where you want carrots to be growing the geraniums would be a weed but if you have a flower garden and carrots started growing in your flower garden you'd pull the carrots the carrots would be a weed so with gemstone it's very subjective it depends on just minerals that look pretty that we value and then you saw that there were some things that are not minerals that can be called gems like pearl and amber so i'd say that most things that are gemstones they are shiny they can be cut into facets and that's like that that classic diamond shape where that reflects the light those are the qualities that most gemstones have yeah i like that question oh man this was really close for a minute but then we have one take the lead oh man math dad are you so excited i stumped them just barely so the sedimentary rocks you're going to be able to see these layers in better but this this this question comes with a bit of an asterisk because it all depends so usually a rock with layers will be sedimentary but metamorphic rocks can often have layers too and that's what we saw with our piece of nice there were some layers in this and this is a metamorphic rock okay so that one wasn't so cut and dry well we'll still let you have your victory bath dab take that all right and we have a bonus question here oh i love this question i'm really curious i purposely didn't talk about this too much because i wanted to see what you guys thought is a glacier a rock is a glacier a rock and remember a rock has to be naturally occurring it has to be formed from minerals and it has to be solid so is a glacier a rock what do you think oh man it's almost died it's almost dead glaciers were not on your chart they were not ooh remington wolfe asked a good question how hard are teeth on the mohs scale they're harder than fingernails but i'm not exactly sure how hard i wouldn't want to test it that's a really good question i think your teeth are stronger than bone the tooth enamel that's my understanding i would have to look it up but that would be a fun one to look up yeah really good question you guys are deep thinkers i like this all right i think it's time to call it and reveal the answer yes a question is a rock i can't believe they got that right so let's go back to this view really fast i think i think that deserves because that last question was kind of a a harder one i think that deserves a victory dance math dad what do you think do you want to show up the victory dance you made for yourself so math dad one of these days i'm actually gonna win and then i'll show my victory dance here here's the math dad victory [Music] that was that was the one that he said he was going to play in celebration and so technically yeah yeah we'll we'll give you a victory mat ted all right is it is a glacier a rock this is a question that if you ask a room full of geologists you will actually entertain some lively debate but most geologists will take that traditional definition of a rock that we just gave you that it's naturally occurring and it is made from minerals and it is solid and so what type of rock is a glacier well what mineral are we referring to here water yes so it's made of the mineral ice and it's a sedimentary rock because you have snow that comes and layers together together and compacts the glacier so most most people will agree that a glacier is a rock which means that we live on a world with an ocean of lava because water is like the melted form of glacier technically that's kind of funny yep um one more question i want to answer real quick before we close um kelly asks why would a cut and polished gemstone be so much more money than just a plain gemstone so for example this piece piece of citrine here when it's cut and polished into a fastened gemstone it's much more valuable part of that is because it's it takes work to cut and polish a gemstone and if you do it wrong then you've got to throw that piece of rock away and get another one and it's it's it takes a lot of work and skill to be able to cut it i think a lot of the value of gemstones is just it's been inflated by the jewelers who want to sell them and like the diamonds are actually a way more common than you would expect based off of the fact that diamond rings cost so much but the prices have been artificially somewhat artificially inflated yes and two really great questions that i'm going to research and i'll have answers for you on friday what's the oldest mineral in the solar system love that question rosalita and then what's the rarest rock that someone could get i would have to do some research for that i will see what i can figure out so on friday we'll be doing some art projects and we'll even get to do some math we do we're going to talk a little bit about ellipses and orbits on friday work hard grow smart and we will see you soon bye

Channel: Science Mom

Views: 1,131,520

Keywords: rocks and minerals, rock identification geology, types of rocks, rock identification

Id: cyBLmW5k06c

Length: 43min 39sec (2619 seconds)

Published: Wed Apr 07 2021