Howardites

The answer sheet for the worksheet Stony-irons: pallasites and mesosiderites. Each answer comes with the reason, so it can be used to mark or to go over the questions with the class.

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Answers: Stony-irons: pallasites and mesosiderites

  1. B: The mantleOlivine is the main mineral of the rocky mantle that surrounds a melted asteroid's metal core.
  2. B: The iron-nickel metalLight passes through the olivine crystals like cellophane, but not through the metal, like foil.
  3. D: Near the surface, where impact melt invaded the mantleOne newer idea is that molten metal from an impact was injected into mantle rock near the surface.
  4. A: Yellow-green to amberPallasite olivine is usually yellow-green to amber.
  5. D: It helped show that rocks fall from spaceIts unusual mix of metal and olivine helped persuade scientists that some rocks really do come from space.
  6. False: the right answer is Different groups may have formed in different waysResearch now suggests the story is more complicated, and different groups may have different origins.
  7. False: the right answer is It is basalt-like rock and pyroxene, not olivinePallasites hold olivine, while mesosiderites hold basalt-like rock and pyroxene similar to Vesta's rocks.
  8. They are rare compared with stony meteorites (accept any answer with the same meaning)About one fall in a hundred is a stony-iron, so they are rare; most falls are stony meteorites.
  9. Some parts of it contain only metal, with no olivine (accept any answer with the same meaning)Seymchan's olivine occurs only in some parts, so it was later recognised as a pallasite.
  10. A pallasite (accept any answer with the same meaning)Olivine crystals embedded in iron-nickel metal are the mark of a pallasite.

Task

Answers will vary. The task comes from the lesson: 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.

Look for work that uses the key words correctly and gives a reason for each point.

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