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The answer sheet for the worksheet Achondrites: rocks from melted worlds. 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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Start here: Explorer · Ages 10 and upAnswer sheet for teachers

Answers: Achondrites: rocks from melted worlds

  1. A: Enstatite, a pyroxene rich in magnesiumAubrites are pale rocks made mostly of enstatite, which formed where oxygen was scarce.
  2. D: They partly melted yet kept chondrite tracesPrimitive achondrites were heated enough to partly melt, but not enough to erase all signs of their origin.
  3. D: AchondritesAchondrites are stony meteorites that formed by melting, so any chondrules they once had are gone.
  4. C: Deeper, beneath the basalt crustEucrites are crust lavas, while diogenites probably formed deeper down.
  5. B: Both melted and separated into layersThe Moon and Mars are differentiated worlds, so their rocks are melted rocks without chondrules.
  6. False: the right answer is It melted and grew a crust very earlyEucrites are crust lavas, so early eucrites show that Vesta melted and built its crust very soon after the start.
  7. True (Melting on their parent body destroyed them)Achondrites were melted, or nearly melted, on their parent body, which wiped out any chondrules.
  8. Both crystallised from molten rock (accept any answer with the same meaning)Achondrites crystallised from a melt, just like Earth's igneous rocks such as basalt and gabbro.
  9. Metal is denser than rock, so it sinks (accept any answer with the same meaning)In a melted body the heavy metal sinks to the middle and forms a core.
  10. A chondrite (accept any answer with the same meaning)Achondrites need a parent body that melted; a rock from a body that never melted keeps its chondrules.

Task

Answers will vary. The task comes from the lesson: Make a layered model of a differentiated asteroid using modelling clay: a grey metal core, a green olivine mantle and a dark basalt crust. Cut it in half and label where irons, diogenites and eucrites would come from.

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

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