Fadan Quartz is a variety of Quartz crystal, a silicon dioxide mineral with a hardness of 7. Its crystal system is hexagonal (trigonal). Faden Quartz is distinguished from other Quartz crystals by the presence of fuzzy white line running through the crystal. The word ‘faden’ is German for fiber, and the derivation of the name of these crystals comes from the resemblance of the internal white line to a strand of white yarn or string. The faden line is usually relatively straight and can vary from about a millimetre to almost an inch in thickness. One possible explanation for the faden line is that the crystals may have fractured and re-grown one or more times, with the line marking the location of the healed fractures.