Himalayan Salt.

Himalayan crystal salt lamps are said to create anions (negatively charged ions) in the air. Since pollution and the use of electrical equipment create potentially harmful positively charged ions (cations) in the air and cause air quality to deteriorate, using a salt lamp helps counter the cations. This natural ionisation helps avoid the physical and mental harm created by the 'electric smog' around us.

Salt lamps can be used either with electric bulbs or
candles depending on the model, both emitting a soft,
golden light that lends visual appeal to a room. Not only
do they look good, they also function as natural air
cleansers. Heat from the bulb or candle make the crystal
salt emit negatively charged ions, which enter the air and
neutralise the positively charged ions created by pollution
and electrical appliances. The neutralised ions become
heavy and fall to the ground.

Himalayas

These lamps are made of natural crystal salt from
underground mines in the Himalayas. The crystal salt is
millions of years old and has a high mineral content as
well as special properties. The cleansing properties of
these lamps are said to help combat illnesses like allergies and asthma. Other sources of anions are waterfalls and the sea; these produce up to 10,000 anions per cubic metre compared to just 100 anions per cubic metre being produced in a city at rush hour time.

Download MSDS here