Colorless, transparent Quartz. Depending on the impurities of various elements, it creates different colored varieties: Amethyst, Citrine, Rose Quartz, Milky, Blue, Smoky, and others. Rock Crystal feels cool to the touch. Due to its good thermal conductivity and high heat capacity, it is always cold to the touch. The name of the stone comes from the Greek “krystallos,” meaning “ice.” For many centuries, the name “crystal” was reserved only for Rock Crystal. The stone has strong cleansing properties. It is called the king of crystals and an energy accumulator.