Zircon (ZrSiO4) forms in magma as it cools into igneous rock. It is also useful for numerical dating. a. If you walk on a modern New Jersey beach, then you will walk on some zircon sand grains. Yet if you determine the numerical age of the zircons, it does not indicate a modern age (zero years) for the beach. Why?
b. Suggest a rule that geologists should follow when they date rocks based on the radiometric ages of crystals inside the rocks.

Zircon is essential element in the formation of igneous ricks.

Explanation:

Zircon crystal commonly grow in rocks and are very small in size. Zircon forms magma ad the lavas as it cools and thus is useful for absolute dating but does not indicate modern age for the beach. Due to the structure of the crystal, as it solidifies in magma. Once make sure that the crystal formed inside the ricks are formed at the same time as the rock itself. As the ricks are formed in different environments just beneath the surface of the earth.