Grey Himalayan Salt Lamp - 2-3kgHigher iron, sulphur and magnesium mineral content gives them their darker colour and they have a much softer glow than pink or white salt lamps. Grey rock salt lamps, also sometimes called black salt lamps, are best for bedrooms where you don't want too much light. By using a Himalayan Crystal Salt Lamp you replace the negatively charged ions in the air which help us to avoid the alleged physical and mental harm that the electric smog creates