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...What the difference between a stalactite and a stalagmite?What is a fossil?What is a Palaeontologist?What is Hybrid Engine Technology?Which is the brightest star in the sky?