How Do Zircons Form?
As a December birthstone, blue zircon is very popular. But are blue zircons natural? Learn how zircons form and get their colors.
8 Minute Read
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
Emily Frontiere
Emily Frontiere is a GIA Graduate Gemologist. She is particularly experienced working with estate/antique jewelry.
International Gem Society
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