mineral

Zircon

Zircon (Zirconium Silicate, ZrSiO4)

Hardness: 7.5 on Mohs scale; Color: Reddish-brown, yellow, or smoky; Luster: Adamantine to vitreous; Crystal structure: Tetragonal; Specific gravity: 4.6-4.7; Cleavage: Indistinct.

Hardness: 7
Color: Reddish-brown, yellow, or smoky
Luster: Adamantine to vitreous

Identified July 1, 2026More mineral →

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Physical properties

Hardness: 7.5 on Mohs scale; Color: Reddish-brown, yellow, or smoky; Luster: Adamantine to vitreous; Crystal structure: Tetragonal; Specific gravity: 4.6-4.7; Cleavage: Indistinct.

Formation & geological history

Forms primarily in igneous rocks such as granite, pegmatite, and syenite. It is very resistant to weathering, often found in sedimentary deposits as detrital grains. It is one of the oldest minerals on Earth, sometimes dating back 4.4 billion years.

Uses & applications

Used as a gemstone, a source of zirconium metal and zirconium dioxide for ceramics, and crucially in geochronology (Uranium-lead dating) to determine the age of rocks.

Geological facts

Zircon crystals are the oldest known materials on Earth. They are incredibly resilient and can survive multiple cycles of erosion and metamorphism, acting as time capsules for geological history.

Field identification & locations

Identified by high refractive index and high density. In the field, look for small, heavy, prismatic crystals in granitic rocks or river sands. It is often confused with quartz but is much harder and heavier.