We bet you thought that rocks are just rocks, but the truth is there are three different kinds of rocks. Learn the differences between sedimentary, metamorphic and igneous rocks. Created by MIT+K12.
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- How about diamond? It is one kind of rock or different category?(17 votes)
- Diamond is a mineral formed by intense heat and pressure. Minerals are made up of elements (carbon for diamonds), and rocks are made up of different minerals.(11 votes)
- can the rock cycle go backwards(3 votes)
- There is no 'backwards' in the rock cycle. Any of the three rock types can be transformed into either of the other types.(8 votes)
- What kind of rock would you find near a stream? Or in your backyard? The rocks that I see don't look like any of those types.(3 votes)
- You would find pebbles or gravel near a stream. In your backyard, it varies on where you live.(2 votes)
- Work with me here. Let's go back 3.2 billion years (1 billion years in) or even 2 billion years, whatever it takes to make my thesis work. How much "rock" was there? I mean there's also organic matter at work here, right? Even sand is created from parrot fish and at just 1 inch a year, 1 million years equals like 14 miles.
Also, igneous rock isn't exactly a new process, it's been around for probably the full 4.2. Spewing out, but replenished how? Clearly it's a cycle of renewal as it melts and consumes the old and spits out the new. Again, at just 1 inch a year......
So, without writing a novel of pure speculation, please allow me to ask: if all rock is the result of organic creation, then isn't this true of all "rock" formations in the universe? Rocks are proof of life, right?(2 votes)
- In my opinion, not all rocks are proof of life. However, sedimentary rocks are made from sediment, which can be made of old life. So, only those type of rocks are proof of life, in my opinion(2 votes)
- is diamond the hardest?(2 votes)
- Diamond is the hardest substance on earth according to the Mohs Hardness scale for minerals and comparing other materials(1 vote)
- diamonds are actually minerals, not rocks. Essentially rocks are MADE UP of minerals. There is no Mineral Cycle though.(2 votes)
- I don't get the difference between a sedimentary rock and metamorphic rock. I also don't get what an igneous rock is. Please help! I'm having a test soon! Reply as soon as possible(ASAP)!(1 vote)
- A sedimentary rock is a rock made from sediment(!) that has been fused together into rock by heat, pressure, or chemical reactions.
An igneous rock is simply any rock that is composed of cooled molten rock.
A metamorphic rock is a rock that has changed by heat and/or pressure into another kind of rock. For example, shale can change to slate, limestone to marble, etc.(2 votes)
- I don't understand, aren't metamorphic rocks still sedimentary since they are made of different sediment, which is why we can see the different bands of color on some metamorphic rocks?(2 votes)
- No. When the rocks goes through the erosion, pressure, and extreme heat, the rock will change to a different chemical structure. That is why the rock is not the same(1 vote)
- I understand the cycle of rocks, but I need to know how they get weathered(3 votes)
- Does each rock have to be formed in a certain order?;-}(1 vote)
- No, each rock can change into any other rock. Ex: Metamorphic to sedimentary to metamorphic to igneous to sedimentary. You should get it now.(1 vote)
(printing machine) (rock music) - [Voiceover] I bet you thought rocks are just rocks, right? (record scratching, music stops) Nope. There are three major types of rocks: sedimentary, igneous, and metamorphic. But the coolest thing about rocks is that each one has the ability to change into the other kind. - Huh? - How is that possible? (rock music) (record scratching, music stops) - [Voiceover] Sedimentary, metamorphic, and igneous rocks change into each other in a process we call the rock cycle. (rock music) (music stops) No, not that kind of rock. This kind of rock. (rock music) (music stops) Yeah, that's more like it. The first type of rock we'll talk about is sedimentary. On the surface of the Earth, wind and water break down rock into tiny pieces. Those pieces might collect in a riverbed, on a flood plain, be swept into sand dunes, or collect on the ground. Over time, layers of these rock fragments build up and start to weigh down on one another. Eventually they get fused together to form sedimentary rocks. The cool thing is that, if you look closely, you can still see pieces of the original rocks or sediment that were bound together. - [Voiceover] Let's do a demo. For our rocks, we're gonna use jelly beans. Each flavor of jelly bean represents a rock or a mineral that has been broken down by wind and water through a process called erosion. We put our jelly beans in this bowl, and add some honey and corn starch, they're the bonding agents to hold our pieces together, kind of like glue for rocks. A little time and pressure has turned our jelly bean pieces of sediment into a brand-new rock. - [Voiceover] So what happens if you apply both heat and pressure? It becomes a metamorphic rock. Metamorphic rock may form by friction of the Earth's shifting crust, pressure deep within the Earth, or even radioactive decay. The heat and pressure cause the rock structure to change so it takes on a new form. Even though it's changed, you can often still see structures of its original components. - [Voiceover] Let's take our sedimentary jelly bean rock and turn it into a metamorphic one with heat and pressure. To add pressure, we'll put this heavy pot on top. For heat, we'll stick it in the oven for about 30 minutes. After it's cooled, you can see how our jelly bean rock has formed a more solid unit. However, you can still see the individual pieces of candy, but the structure has fundamentally changed. - [Voiceover] The third type of rock in the rock cycle is igneous. When rocks get super-heated deep within the Earth, they melt and form a liquid called magma. If magma rises to the surface or moves up in the Earth's crust, it begins to cool. Igneous rocks have a uniform structure throughout, but will have different properties depending on whether they cooled on the Earth's surface or within the crust. - [Voiceover] To turn our jelly bean metamorphic rock into an igneous rock, we're gonna melt it in this pot of boiling water. When our rock is cooled, you can see how all the different pieces combined to make an igneous rock, with uniform structure throughout. Pretty cool, huh? - [Voiceover] But this is only part of the story. We showed you one path for the rock cycle, but really any rock can go from one type to another. For example, igneous rocks can turn into either metamorphic or sedimentary. And metamorphic rocks don't have to become igneous rocks, they can be broken down again and become sedimentary. Or, the sedimentary rocks can get pushed deep within the Earth to form igneous. See? All of the rock types are connected, making a cycle that never ends. The end! (rock music) ♫ - We are the rocks of the world ♫ Whoa, ho ho, rocking ♫ We are rocking so much ♫ Until the night ♫ Rocking baby, whoo oh ♫ Rock it to the beat ♫ Rockin' baby ♫ Whoo, whoo ♫ Rocking until the sun comes up ♫