Think of each crystal as giving off a tone, or frequency unique to itself. The cluster emits a symphony of vibrations. These crystals can be placed in areas where you want to create a stronger healing vibration or to cleanse the atmosphere. Look for crystal clusters with thin sandstone or no rock matrix behind it. That way you get more crystals and hardly any opaque matrix rock for your money. When placing clusters on furniture, always use a cloth, pillow or pad under the crystals, as the sharp rock on the bottom will scratch your furniture.
Clear quartz is pure silica. When it contains tiny bubbles of water or gases, part of the crystal will appear misty or milky white.