What is Zircon? Zircon is the oldest known mineral crystal which belongs to the group of nesosilicates. They have been found in some igneous rocks which scientist believe date back 4.4 billion years ago. Its chemical name is zirconium silicate. Other interesting facts...Which is the brightest star in the sky?Some Electrifying FactsWhat is a Lunar Eclipse?Who was Rosalind Franklin?What is the Crab Nebula?