Howardites

A printable worksheet for the lesson Iron meteorites and their hidden patterns (Start here: Explorer). It prints on A4 without the website around it. The answers are on a separate sheet for the teacher.

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Start here: Explorer · Ages 10 and upHowardites worksheet

Iron meteorites and their hidden patterns

Name:Class:Date:

Key words

Iron meteorite
An iron meteorite is made mostly of iron and nickel metal.
Asteroid
A rocky or metal-rich object, smaller than a planet, that goes around the Sun.
Widmanstätten pattern
The criss-cross pattern of metal bands that appears when many iron meteorites are cut, polished and etched.
Kamacite
The nickel-poor form of iron-nickel metal in meteorites, forming the broad bands of the Widmanstätten pattern.
Octahedrite
The most common structural class of iron meteorite, showing a criss-cross Widmanstätten pattern when etched.
Ataxite
A nickel-rich iron meteorite that shows no visible structure when etched.

Choose the right answer

Circle the letter of the right answer.

  1. What is troilite, which often forms nodules inside iron meteorites?
    • AAn iron sulphide
    • BA form of diamond
    • CA glassy outer crust
    • DA nickel-rich metal band
  2. An iron with about 5 per cent nickel is almost all kamacite and shows fine parallel lines. Which class is it?
    • AMesosiderite
    • BAtaxite
    • CHexahedrite
    • DOctahedrite
  3. Why did metal collect at the centre of some young asteroids?
    • AComets dropped metal into their middles
    • BMelting let the dense metal sink inwards
    • CMetal grew there slowly from cold dust
    • DThe Sun's gravity dragged the metal inwards
  4. Which pairing of meteorite and class is correct?
    • AGibeon, a fine octahedrite
    • BHoba, a coarse octahedrite
    • CGibeon, an ataxite
    • DHoba, a hexahedrite
  5. How are coarse, medium and fine octahedrites told apart?
    • ABy how many troilite nodules they hold
    • BBy the colour of the etched surface
    • CBy the width of their kamacite bands
    • DBy the size of the whole meteorite

True or false?

Is the answer given right? Tick True or False.

  1. Which statement about kamacite and taenite is correct?

    Answer given: Taenite is low in nickel and forms broad bands TrueFalse

  2. Why are iron meteorites so useful for understanding Earth's own core?

    Answer given: We cannot sample Earth's core directly TrueFalse

Write your answer

Answer in a word or a short sentence.

  1. What produces the Neumann lines seen in many hexahedrites?
  2. Where does the name octahedrite come from?
  3. An iron has about 9 per cent nickel and shows criss-cross bands. Which class is it?

Task

Look at pictures of an etched iron meteorite and try drawing the pattern. Notice how the bands cross at a few set angles. Can you find the thin bright borders of taenite?

Howardites · free to copy for use in your classroom · answers are on the separate teacher's answer sheet