Zircon (ZrSiO₄)

Tetragonal zirconium silicate, source of the oldest dated Earth material (4.404 Ga) and principal zirconium ore.

Specifications & Metrics

type

Nesosilicate Mineral

formula

ZrSiO₄ (tetragonal)

crystal system

Tetragonal

hardness

7.5 Mohs

refractive index

nω 1.925–1.961 / nε 1.980–2.015

density

4.6–4.7 g/cm³

melting point

≈2,550 °C (fusibility; varies with Hf, Th, U content)

phase transition

Metamictization (radiation-damaged amorphous state); refractive index falls to 1.75 when metamict

Core Principles & Analysis

• Zircons from the Jack Hills of Western Australia have yielded U–Pb ages up to 4.404 billion years — the oldest minerals so far dated on Earth.
• The name derives from the Persian zargun ('gold-hued'); orange-red gem zircon is called hyacinth and pale stones jargoon.
• Heating brown zircon to 800–1,000 °C transforms it into colorless and blue gemstones, and Australia produces 37% of the world's zircon.

Sources

• Wikipedia: Zircon