Science, Maths & Technology
How to read a rock
...change its chemical characteristics through time, and therefore so will the zircon crystal, growing continuous concentric ‘zones’ of progressively different chemistry, until the molten rock has cooled enough and has solidified. Each of these zones, therefore, preserves a chapter in the life of the rock. [Zircon] This zircon grain is smaller than a grain of sand. This...