How Do Zircons Form?

Where Do Zircons Form?

Zircons form in many geological environments, including igneous, metamorphic, and sedimentary rocks.

Zirconium Origins

Zircon crystals of igneous origin have an extremely high melting point. They can form within silicic magma as it slowly cools. In this situation, the mineral baddeleyite will melt and provide zirconium (Zr), a necessary ingredient for zircon formation. Under metamorphic conditions, the zirconium in surrounding minerals like baddeleyite can leach out of the mineral and recrystallize into zircon when existing rocks partially melt.

Zircon Overgrowth

Secondary zircon stones can also recrystallize from liquified primary zircon or form a new outer layer on top of the older zircon crystal in a process termed “overgrowth.” Zircons with multiple layers may or may not show obvious zones.

Metamorphic Zircons

Metamorphic zircon formation can lead to three distinct forms:

• Bead zircons (tiny individual crystals