grains of zircon

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Senior Member

Uranium-lead dating allowed them (two geologists) to go about it in an entirely different way. What they did was they looked at the grains of zircon in the sandstone. Zircon is a material that contains radioactive uranium, which makes it very useful for dating purposes.

(This comes from a TOEFL listening transcript about a lecture in a geology class on a Chinese website.)

1. Does "grain" here mean "a small hard piece of particular substances", not "the natural direction of lines in wood, cloth, etc. or of layers of rock"?
2. Does "grains of zircon" mean "particles which are zircon", like "the city of Beijing"?

Thanks in advance!
  • Hildy1

    Senior Member
    English - US and Canada
    1. That is the way I understand it.

    2. "Grains of zircon" means "particles that are zircon", but in a different way from "the city of Beijing" (= the city whose name is Beijing). It's more like "a slice of cake" or "a ball of cotton".

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