Howardites

A printable worksheet for the lesson Stony-irons: pallasites and mesosiderites (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

Stony-irons: pallasites and mesosiderites

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Key words

Stony-iron meteorite
A stony-iron meteorite is made of roughly equal amounts of metal and rocky minerals.
Pallasite
A stony-iron meteorite with green olivine crystals set in a network of shiny iron-nickel metal.
Olivine
A green mineral that is very common in meteorites and makes the gem called peridot.
Crystal
A crystal is a solid in which atoms are arranged in a neat, repeating three-dimensional pattern.
Silicate
A silicate is a mineral built around silicon and oxygen, the main ingredient of rocky planets and stony meteorites.
Mesosiderite
A stony-iron breccia made of iron-nickel metal mixed with broken basaltic and pyroxene-rich rock.

Choose the right answer

Circle the letter of the right answer.

  1. In a melted asteroid, which layer is rich in olivine?
    • AThe surface dust
    • BThe mantle
    • CThe thin outer crust
    • DThe metal core
  2. In the cellophane and foil model, which part of a pallasite does the foil stand for?
    • AThe melted outer crust
    • BThe iron-nickel metal
    • CThe pyroxene fragments
    • DThe olivine crystals
  3. Where have some researchers more recently suggested pallasites formed?
    • AInside the Sun, long before any of the planets formed
    • BDeep in the very centre of the core, far from any rock
    • COn Earth, inside the vents of erupting volcanoes
    • DNear the surface, where impact melt invaded the mantle
  4. What colour is the olivine in a pallasite usually?
    • AYellow-green to amber
    • BChalky white
    • CBright ruby red
    • DDeep sapphire blue
  5. Why was the Krasnojarsk meteorite important in the history of science?
    • AIt proved that the Moon once had active volcanoes
    • BIt was the first meteorite ever used to make iron tools
    • CIt was the first meteorite that anyone saw fall
    • DIt helped show that rocks fall from space

True or false?

Is the answer given right? Tick True or False.

  1. Which statement best matches current thinking about pallasites?

    Answer given: Pallasites are pieces of the metal core of the Moon TrueFalse

  2. How is the rock in a mesosiderite different from the rock in a pallasite?

    Answer given: It is packed full of small unmelted chondrules TrueFalse

Write your answer

Answer in a word or a short sentence.

  1. Stony-irons make up only about one per cent of observed falls. What does this tell us?
  2. Why was the Seymchan meteorite first classified as an iron?
  3. A polished slice shows clear amber crystals set in shiny metal. What is it most likely to be?

Task

Hold a piece of green or amber cellophane up to a window, then hold a piece of foil next to it. A pallasite slice combines both effects: light shines through the crystals but not through the metal.

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