Three kinds of meteorite
Scientists sort meteorites into three main kinds by what they are made of: stone, iron, or a mixture of both.
- Name the three main kinds of meteorite.
- Describe how each kind looks and feels.
- Use a fraction or percentage to say which kind is most common.
Links to: Year 3 science, rocks: comparing and grouping rocks on their appearance and physical properties; maths: fractions and percentages.
Stony meteorites
Most meteorites are stony meteorites. They are made mainly of rock, with small specks of shiny metal scattered through them. Inside, many are grey, a bit like concrete.
The most common stony meteorites are called chondrites. They are packed with tiny round grains called chondrules, often smaller than a grain of rice. Chondrules were drops of melted rock that floated in space before the planets formed. Chondrites are the oldest rocks you can hold.
Iron meteorites
Iron meteorites are made almost entirely of metal: iron mixed with nickel. They are very heavy for their size and a magnet sticks strongly to them.
Iron meteorites come from the centres, called cores, of asteroids that once melted. The heavy metal sank to the middle, just as Earth has a metal core. When those asteroids were smashed apart, pieces of the core flew into space. The biggest meteorite ever found, Hoba in Namibia, is an iron weighing about 60 tonnes.
Stony-iron meteorites
The rarest kind, stony-iron meteorites, are roughly half rock and half metal. The most beautiful are pallasites, which have green or golden crystals of a mineral called olivine set in shiny metal, like stained glass. When a thin slice is held up to the light, light shines through the crystals.
Which kind is most common?
Out of every 100 meteorites that people see fall, about 94 are stony, about 5 are iron and about 1 is stony-iron. If 300 meteorites fell and were found, about how many would be iron?
- About 5 out of every 100 are iron. That is 5%.
- 300 is 3 lots of 100, so multiply: 3 × 5 = 15.
Answer: About 15 of the 300 would be iron meteorites, and about 282 would be stony.
Make a sorting table with three columns: Stony, Iron, Stony-iron. Draw or describe one example in each column, and add words about how it looks: colour, shininess, specks of metal, crystals. If your school has rock samples, compare them with your table.
Quiz
5 questions. Choose an answer to see whether you are right and why. Finish the quiz to complete the lesson.
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Question 1Which is the most common kind of meteorite?
About 94 out of every 100 meteorites seen to fall are stony.
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Question 2What are chondrules?
Chondrules formed as melted droplets floating in space before the planets formed, and they are found in chondrites.
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Question 3What are iron meteorites mostly made of?
Iron meteorites are iron and nickel metal from the cores of asteroids that melted.
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Question 4What makes pallasites special?
Pallasites are stony-irons with crystals of olivine held in shiny metal, which let light through when a thin slice is held up to a window.
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Question 5About 5 out of every 100 meteorites are iron. About how many iron meteorites would you expect among 200?
200 is 2 lots of 100, and 2 × 5 = 10.