Howardites

The answer sheet for the worksheet The classification framework. 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: The classification framework

  1. C: With achondrites, from differentiated bodiesAchondrites, irons and most stony-irons all derive from bodies that underwent substantial melting.
  2. B: Their mineral compositions are diagnosticFor these well-characterised groups, mineral compositions and petrography are usually enough.
  3. A: 12 gThe rule is 20 per cent or 20 g, whichever is less; 20 per cent of 60 g is 12 g.
  4. C: Paired stones are one fall, not independent samplesFive fragments of one fall tell us about one meteoroid, not about a population from a parent body.
  5. A: It can be defined as a groupFive unpaired members meet the minimum for a group, so new groups are defined as members accumulate.
  6. True (One fall can yield many separately found stones)Without careful pairing, fragments of one fall would be counted as many separate meteorites.
  7. False: the right answer is Location, mass, pieces, data and classifiersSubmissions give the fall or find location, mass, number of pieces, classification data and the classifiers' names.
  8. As a grouplet (accept any answer with the same meaning)Sets of two to four unpaired, related meteorites form a grouplet; a group needs at least five.
  9. After a type meteorite (accept any answer with the same meaning)Most carbonaceous groups take their letter from a type meteorite, which is why CH is an exception.
  10. Chondrites, primitive achondrites, melted bodies (accept any answer with the same meaning)The first division is by degree of processing: undifferentiated, partly melted, and melted and differentiated.

Task

Answers will vary. The task comes from the lesson: Draw a tree diagram with chondrites, primitive achondrites and achondrites as the first branches, then add classes, clans and groups. Place each meteorite named in this course on its branch.

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

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