magnified zircon crystal showing crystal growth age dating Yellowstone

Sections of a zircon crystal, only 100 micrometers across, showing stages of the crystal's growth. Upper panel shows the outer surface of the crystal, which is 131,000 years old based on 238U-230Th dating. This is when the crystal stopped growing. Lower panel shows the interior of the same zircon crystal. The dark central growth zone of the zircon is 196,000 years old, which is when the zircon crystal started growing. Dating of the intermediate, gray growth zone yielded an age of 154,000 years old. Together, these data demonstrate that this crystal grew over 65,000 years, although this growth was not necessarily continuous and may have occurred in spurts.