# Learn About Different Type of Meteorites - Octahedrites, Chondrites, Pallasites, Martian Shergottites, Lunar Lunaites.


![](https://steemitimages.com/DQmbqzD5v1GY5NEQ9kfoyc19VNf3cV9r5TnKMuptbxSR6bR/image.png)
Image Credit:- [wikimedia](https://en.wikipedia.org/wiki/Lunar_meteorite#/media/File:Allan_Hills_81005,_lunar_meteorite.jpg)

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# Introduction

Today I am going to write to you about **Meteorites**, what they *are*, where you can *find* them, how to *identify* if you have one. I will also show you *examples of craters left by the impacts*, and what *geologic specimens* remain. You'll learn about the *different types of meteorites* and hopefully be surprised and intrigued by the information.

Firstly the term meteorite is given to a space debris of a geologic nature (so not satellite junk) that has managed to travel through the atmosphere without completely disintegrating. 

>**I wrote an article before about the difference between asteroids, meteors, comets etc. If you aren't sure then I suggest to read the article here:-**

>[How to Tell the Difference....Comets, Asteroid, Meteors, Meteoroids, Meteorites and Shooting Stars](https://steemit.com/howto/@physics.benjamin/how-to-tell-the-difference-comets-asteroid-meteors-meteoroids-meteorites-and-shooting-stars)



![](https://steemitimages.com/DQmePYNWEkjmqcQfHMCJYHMCzoTrvZoqzwqyGGMcXSba96x/image.png)
Image Credit:- [wikimedia](https://en.wikipedia.org/wiki/Meteoroid#/media/File:Leonid_Meteor.jpg)

Everyday 100 tons of dust, sand-sized particles and small rocks enter the earths atmosphere. The dust and small particles calmly fall as their mass is small, but the pebble sized rocks are large enough that they accelerate in Earth gravitational field and very quickly gather speed. By the time they reach Earths atmosphere they are already moving at at least 10,000 Km per second. Once they encounter Earths atmosphere the air pressure or the force they feel from air resistance is so strong due to their velocity that huge frictional forces are experienced. This friction does two things, it slows the small meteoroid down to terminal velocity, and heats it up to over 1,600 Celsius. This immense heat causes the meteoroid to glow white hot creating the effect of a shooting star, it also melts the rock or iron and due to air resistance this molten material is stripped away. In fact due to this process only about 5% of meteoroids (bigger than dust/particles) actually impact the Earth because they burn up in the atmosphere. If you have been lucky enough to see a shooting star its most likely burnt up in the atmosphere, but the spectacular ones that are like fireballs sometimes make it to the ground, there are no craters formed just little holes. But you need to be quick to find them, they are all very rich in iron content so is at the mercy of weathering and oxidisation (rust). A good place to hunt for meteorites is in deserts such as the Australian outback or Antartica (Yes it's a desert, it never rain and is extremely dry) using a metal detector. 


![](https://steemitimages.com/DQmevQ8wXVXcvb3gvWtS6h9dC3kLB8Dy2NQfoew7UcgFfTU/image.png)
Image Credit:-[wikimedia](https://en.wikipedia.org/wiki/Morasko_Meteorite_Nature_Reserve#/media/File:Morasko_krater_zima.jpg)

>Above you will see a small crater is Poland, **Morasko** it's about 30 m in diameter and is believed to have occurred about 5000 years ago. In 2006 a meteorite hunter uncovered a specimen with a metal detector that weighed 164 Kg, that's quite a beasty rock!


Lager meteoroids (25m or more in diameter before burning up) that occur every few years will have so much kinetic due to their mass that frictional forces will not be able to slow it down considerably, the meteoroid will impact with a significant fraction of it's escape velocity which creates an impact crater; you can an example in the image above: Morasko crater. 


Every few thousand years a meteor the size of a football pitch makes it way to earth, they are considered dangerous, but not planetary threatening. These massive rocks from space truly leave their mark and scar the face of the Earth. They leave tremendously big craters and my favourite example is the **Barringer Crater** located in Arizona, USA. This is believed to have occurred about 50,000 years ago, and left a crater 1.2 Km in diameter. It was formed by an **Iron-nickel** meteorite that on impact was only about **50 m** wide, it impacted with a speed of about 20,000 Km per second. It was the huge velocity and mass of the heavy Iron meteorite that gave the impact and energy equivalent to 10 mega-tons of TNT. The majority of the meteorite was vaporised from the heat generated at impact, the largest piece found was the size of a coffee table. 

Impacts of objects larger than 500 m will significantly effect life on life, let's hope we don't ever witness such event. This can be left for another article in the future, so consider following me if you're interested.

![](https://steemitimages.com/DQmZGJZkhtFd8PvNek8vV7cz3Y2VGSFTNVVkNFGDT23JYaN/image.png)
Image Credit:- [wikimedia](https://en.wikipedia.org/wiki/Meteor_Crater#/media/File:Meteor_Crater_-_Arizona.jpg)
> The Barringer Crate located in Arizona, USA. Formed by a Iron-Nickel Meteor impact 50,000 years ago. It's diamter is 1.2 Km, the black rectangle you see is a car park, and the small specks are trucks. It's BIG isn't it.

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# How to Identify A Meteorite And What To Do

Now I'll give you a little explanation about how to identify if you have a meteorite. We can start with simple identification clues, but to confirm it we must take it for special analysis.

Almost every meteorite specimen ever found has contained considerable quantities of iron, such that if you have a sensitive magnet, it will be attracted to the meteorite. This is one clue that it may be meteorite. Also the meteorite experiences a great deal of heating when burning through the atmosphere, so you can look to see if you can spot traces of this. 
For a rocky meteorite it will have a burnt shell, almost like a think black egg shell around it. As for an iron meteorite you want to look if you can see some blackening but more prominent will be deformation lines from the iron melting, stretching and solidifying on it's surface. One feature common to all types of meteorites is that when they enter the atmosphere, it starts to sculpture the meteoroid, and more often than not leaves imprints like thumbprints on the surface, these are called regmaglypts.

#### You can see examples of these mentioned features below. Do you have anything similar??


![](https://steemitimages.com/DQmYNqhcqmDh2GCjqDNS7UR6bbQ2RA4PfNQdW8H8V8cRKWr/image.png)
Image credit:- [wikimedia](https://en.wikipedia.org/wiki/Meteorite#/media/File:Oriented_Taza_Meteorite.jpg)
> This is an iron-nickel meteorite, notice the **blackening** and the **stretching lines at the "head"**, this is from immense heat melting the iron then the air resistance pulling the iron making it look **stretched**.
> 


![](https://steemitimages.com/DQmUAqFwofEQ4cBUW2gD7qorUCkaznHVhNx6jxCd9fNKbVn/image.png)
Image Credit:- [wikimedia](https://en.wikipedia.org/wiki/Chondrite#/media/File:AllendeMeteorite.jpg)
>This is a Chondrite, a stony meteorite. Notice the **black egg shell feature** on it's surface. This is characteristic of meteorites that burnt during their descent through the atmosphere.
>

![](https://steemitimages.com/DQmRQh6vJfhgtzPxwuEHSA4YZUdiLMRvsXsNs6m2nkQ7Ju4/image.png)
Image credit:- [wikimedia](https://en.wikipedia.org/wiki/Meteorite#/media/File:Murnpeowie_meteorite.jpg)
> This is an Iron meteorite that clearly shows the **regmaglypts**. The decent through the atmosphere generates so much heat that the surface iron starts to boil and spits out chunks of iron. You can see that effect here. I wouldn't like to get hit by molten iron ouch!


####  Remember a meteorite is attracted by a magnet due to it's iron content.

#### Look for a black shell on the outside of rocky-like meteorites. Does is have sculptured features?

#### Iron meteorites are black, stretched, and have thumbprints or regmaglypts



These are just superficial characteristics, to be sure that the specimen is truly from space we need to perform chemical analysis and radio-isotope measurements. With this data scientists are able to confirm if it truly is a meteorite, also with this data they can identify where it came from. They can tell if it came from the same parent body, if its a new type, or if it came from a different planet. The chemical composition and isotope ratio is a fingerprint and provide a wealth of data.

### If you think you have a meteorite then take it to your local Museum and ask them for their opinion, they are very helpful.

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# Different Types of Meteorites 

There are main families of meteorites with a large number of specific specimens, we'll look at the families of them, focusing on their composition, origin and characteristic properties.

## Iron Nickel 

![](https://steemitimages.com/DQmTKQ2KvgTu3Q1hMC6NdS14tAqtpEpmuJ5Hr6q8vDztfTi/image.png)
Image Credit:- [wikimedia](https://en.wikipedia.org/wiki/Iron_meteorite#/media/File:SikhoteAlinMeteorite.jpg)

Iron-nickel meteorites are one type that make up 5.7% of all meteorites that make their way to Earth. These meteorites consist 95% of an iron-nickel alloy with some zinc and other metal accounting for the other 5%. There are two main categories called hexahedrites and octahedrites, with another rare family called ataxites. Hexahedrites contain very little nickel and show no Widmanstatten pattern. Octahedrites are the most common iron meteorite they contain and average amount of nickel and this family shows something called the Widmanstatten pattern. This is an interesting feature, it is showing crystal like structure. During it's formation the iron was hot and cooled, during it's cooling it formed a lattice structure. This structure can be studied and provides information on the cooling rate and size of the parent of this meteorite, which originates from the asteroid belt between Mars and Jupiter.

![](https://steemitimages.com/DQmdE6h5fBfNsKJELE82MY4Q2fQHSaktNepAGJqU7q6S4Mn/image.png)
Image Credit:-[wikimedia](https://en.wikipedia.org/wiki/Iron_meteorite#/media/File:Seymchan.jpg)


## Stoney Meteorites - Chondrites, Achondrites

![](https://steemitimages.com/DQmZckQr1k7HsxPYaxH1LedSdSLCkXBZkx4hxV3e1qk2kAP/image.png)
Image Credit:- [wikimedia](https://en.wikipedia.org/wiki/Chondrite#/media/File:M%C3%A9t%C3%A9orite_de_Saint_Sauveur_MHNT2.jpg)

These are the most common types of meteorites that impact Earth they make up 86% of all impacts. They contain some iron but very little, a magnet will be attracted to it still. The chemical composition is quite vast it contains a number of different elements but are mainly silica minerals. It's the formation of silica minerals that differentiates the two types; Chondrites and Achondrites. Chondrites contain something called chondrules, these are fascinating, they are tiny little spheres of rock that originated floating in free space and solidified as a tiny ball, later being gravitationaly crushed into a larger rock. Achondrites do not contain these chondrules they are more similar to rock on earth and are basalt like.

![](https://steemitimages.com/DQmTqvaA6Xfj3rzmKHEGNAKS8uSEVgh1A1HWZutuAUCWbUo/image.png)
Image credit:-[wikimedia](https://en.wikipedia.org/wiki/Chondrule#/media/File:Chondrules_grassland_1.jpg)
> These are the chondrules that formed if free space as tiny little spheres from molten material in the early formation of the solar system.


![](https://steemitimages.com/0x0/https://steemitimages.com/DQmPM2S3oWJDXa8j1f5M2MHyGgPxTejJZ9Lr3BbxgcsrVhu/image.png)


## Stoney Iron - Pallasite


![](https://steemitimages.com/DQma99JzGnS84B9ntZQLzu3axG47Z13Cpxm9mQ4FC7AgovS/image.png)
Image Credit:-[wikimedia](https://en.wikipedia.org/wiki/Pallasite#/media/File:Esquel.jpg)

This is a Pallasite, it is a beautiful act of nature I think, you can see the body is made from Iron-nickel, but it contains pockets of crystals which is olivine crystals of peridot. In the early formation of our solar system the molten iron and minerals formed together in space, as they cooled over time the minerals were able to crystallise into these crystals in small pockets of the iron that surrounded it. These are rare impacts, specimens can be found but they are pricey compared to the others mentioned so far. If the meteor has time to weather the crystals will fall out and all that remains is a strange iron core, which looks bizarre.

## Lunar Meteorite - Lunaite

![](https://steemitimages.com/DQmbqzD5v1GY5NEQ9kfoyc19VNf3cV9r5TnKMuptbxSR6bR/image.png)
Image Credit:- [wikimedia](https://en.wikipedia.org/wiki/Lunar_meteorite#/media/File:Allan_Hills_81005,_lunar_meteorite.jpg)

This is probably my favourite type because of how it got to Earth. These are meteorites which means they fell from space, something must have forced them from the Moons surface. When a large impact occurs on the Moon because of it's weak gravity some of the material completely leaves the surface and goes flying into space, and by small cosmic chances these sometimes impact on Earth. It's incredible! The reason we know they are lunar is because we have been able to match isotopes with specimens taken from apollo missions. The composition is of basalt very similar to that of Earth, but the radioactive isotopes tell us it's lunar and not terrestrial. There are only 306 confirmed Lunaites that have been found. If you have one of these keep it very safe.

## Martian meteorite 

![](https://steemitimages.com/DQmPmMkozHE2miZPcwzAhXrqUhapmAgpHvXnEEbNXRGYNCD/image.png)
Image Credit:- [wikimedia](https://en.wikipedia.org/wiki/Martian_meteorite#/media/File:MarsMeteorite-NWA7034-716969main_black_beauty_full.jpg)

In the same way that meteorites come from the Moon, it can also happen on Mars. For this type of event to occur is crazy, for a human to find one and think it might be interesting, after it came from Mars and teared through our atmosphere, it's mad. There are three classes that have been identified, Shergottites which are basalt like, nakhlites which are also basaltic but contain olivine crystals, and chassignites which are similar but contain trace of oxygen. Again these were proved to originate from Mars because the Mars Rover was able to analyse the geology on Mars and send results to Earth, so we can check the chemical fingerprints.


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## Conclusion

So I hope you enjoyed this article, clearly we have Just covered the basics, this is a whole field of study and takes years to fully understand. However I am sure you'd agree this is very interesting material, and if you ever find a strange looking rock you know what to do if you think it's fallen from space. Is it magnetic? Does it look burnt? Does it look like it's fallen from space? And if you see and crystals in it you've hit the jackpot.


















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References:-
[Space.com](https://www.space.com/33695-thousands-meteorites-litter-earth-unpredictable-collisions.html)
[Nasa.gov](https://www.nasa.gov/mission_pages/asteroids/overview/fastfacts.html)

[Wikipedia](https://en.wikipedia.org)
* Meteorites
* Morasko Meteorite Nature Reserve
* Lunar Meteorite
* Martian Meteorite


_All images are Creative Commons or public domain, no copyright infringements have occurred._