Many zircon crystals contains trace amounts of uranium and thorium. These radioactive elements were incorporated into the zircon at the time of crystallization. They convert into their decay products at a steady rate. The ratio of parent materials to daughter products can be used to estimate the time of crystallization. Using this method, the oldest…

Zircon sand has a low expansion coefficient and is very stable at high temperatures. It is used as a refractory material in many foundry and casting applications. One of its most common uses is in the production of ceramics. Zirconium dioxide (zirconia) is produced by heating zircon sand to a high enough temperature to break…

There is much public confusion between four materials: zircon, zirconium, zirconia and cubic zirconia. Summary definitions of these terms are provided below. Zircon is a naturally occurring mineral with a chemical composition of ZrSiO4. Zirconium is a silvery white metal and a chemical element. It has an atomic number of 40 and an atomic symbol of Zr.…

Zircon has been mined from stream gravels for over 2000 years. This early mining of zircon was mainly to obtain nice crystals for use as gemstones. Today, most zircon is produced by mining or dredging zircon-rich sediments. These sediments can be in beach, littoral, or alluvial deposits. Zircon has a specific gravity of 4.6 to…

Most blue zircon sold in jewelry today is produced by heat treating brown zircon in a reducing atmosphere to 900 to 1000 degrees Celsius. Some people have damaged these blue zircons by exposing them to ultraviolet radiation in tanning beds or under ultraviolet lamps used to cure acrylic fingernail adhesives. The blue color can degrade…

Zircon has been used as a gemstone for over 2000 years. Its very high dispersion and refractive index give it a brilliance and fire that rival those of diamond. For that reason, colorless faceted zircon has been used as both a popular and fraudulent substitute for diamond. Gemologists and many knowledgeable jewelers are able to distinguish…

Zircon is a primary accessory mineral in most granitic rocks. It is also present in gneiss and other rocks derived from the metamorphism of zircon-bearing igneous rocks. Zircon is so common and widely distributed across the rocks of Earth’s surface that it could be considered to be a ubiquitous mineral. However, zircon is usually not noticed in rocks…

Zircon is a zirconium silicate mineral with a chemical composition of ZrSiO4. It is common throughout the world as a minor constituent of igneous, metamorphic, and sedimentary rocks. Zircon is a popular gemstone that has been used for nearly 2000 years. Today it serves as a modern birthstone for the month of December. Zircon occurs in a wide range of colors and has a brightness…