Clear Quartz also known as Rock Crystal ranges from white (opaque) to clear (transparent), and belongs to the rock crystal family of stones. All rock crystals are composed of SiO2 They form according to a trigonal crystal structure, and have a hardness of 7 on the Mohs scale. ‘Phantoms’ represent growth spurts in the crystals formation and can come in lots of different colours depending on the minerals present. On rare occasions during formation, the crystal will stop growing and different minerals may start to settle on the surface of the solidifying crystal, at a later stage the ‘mother’ liquid starts flowing again and the crystal starts to grow. This stop start process can happen multiple times causing multiple phantoms. Green phantoms in quartz are usually Chloride.