A Cluster-Crystal is a group of crystals that have formed or grown together in a group or a cluster.   Clear Quartz is also known as Crystal Quartz or Rock Crystal.  It is colourless Quartz, a natural form of silicon dioxide. Clear Quartz is known as the "master healer" and will amplify energy and thought, as well as the effect of other crystals. It looks especially beautiful with the sunlight shining through it .  It is fragile and will damage if dropped .... it is 7 cm in width .