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A printable worksheet for the lesson Petrologic types: from wet to hot (Start here: Enthusiast). 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: Enthusiast · Teens and adultsHowardites worksheet

Petrologic types: from wet to hot

Name:Class:Date:

Key words

Chondrite
A chondrite is a stony meteorite full of tiny round grains called chondrules, and almost unchanged since the Solar System formed.
Petrologic type
The petrologic type is a number from 1 to 7 added to a chondrite's group to show how much it was altered by water or heat on its parent body.
Thermal metamorphism
Thermal metamorphism is the slow heating of rock inside an asteroid, below its melting point, which recrystallises minerals and blurs original textures.
Chondrule
A chondrule is a tiny round grain, often smaller than a grain of rice, that formed as a melted droplet in space before the planets existed.
Olivine
A green mineral that is very common in meteorites and makes the gem called peridot.
Feldspar
Feldspar is a family of pale silicate minerals rich in aluminium, and the commonest mineral group in Earth's crust.

Choose the right answer

Circle the letter of the right answer.

  1. What are presolar grains?
    • AGrains formed in the Sun's own outer layers
    • BDust swept up during atmospheric entry
    • CCrystals that grew in water inside the parent body
    • DStardust made around other stars before the Sun
  2. Allende is classed as a CV3. What does the 3 tell you about it?
    • AIt was strongly heated and recrystallised
    • BIt was heavily altered by liquid water
    • CIt was the third CV chondrite to be found
    • DIt is among the least altered chondrites
  3. Why are type 3 chondrites described as 'unequilibrated'?
    • ATheir grains never swapped atoms, so they differ
    • BTheir chondrules are all exactly the same size and age
    • CThey were heated unevenly by later impacts
    • DTheir weight cannot be measured accurately
  4. Where did the liquid water that altered type 1 and 2 chondrites come from?
    • ARain soaked the stone after it reached Earth
    • BIce in the parent body melted as it warmed
    • CWater formed in the heat of atmospheric entry
    • DComets later crashed into the parent body
  5. A CI1 and a CM2 are compared. Which has been more altered by water?
    • ANeither
    • BThe CM2
    • CBoth equally
    • DThe CI1

True or false?

Is the answer given right? Tick True or False.

  1. Why is type 7 used with caution?

    Answer given: It marks the most water-altered chondrites TrueFalse

  2. Why are thermoluminescence and the chromium in olivine used to set type 3 subtypes?

    Answer given: They record when the meteorite fell TrueFalse

Write your answer

Answer in a word or a short sentence.

  1. Which evidence broadly supports the onion-shell model?
  2. Roughly what temperatures were typical for this metamorphism?
  3. What would you expect to find inside many chondrules of a type 3 chondrite?

Task

Draw a horizontal line labelled 1 to 6. Mark type 3 in the middle as pristine, write water above types 1 and 2, and heat above types 4 to 6. Add examples from this course to the line as you meet them.

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