NOW Colloidal Minerals is an effective source of naturally derived, colloidal major and trace minerals. This proudct has been carefully water processed and then screened with a proprietary micron-filter process to remove or reduce virtually all major heavy metals to harmless levels. Contains less than 1 ppm of arsenic, cadmium, lead and mercury. The mineral levels listed are typical levels and do vary from batch to batch. NOW Colloidal Minerals is a unique source of highly absorbable, water-soluble minerals and trace elements derived from prehistoric plant deposits. Each serving contains a concentrated solution of colloidal minerals from humic shale. These colloidal minerals were created ages ago when they became incorporated into the living plants, fruits and vegetables of the ancient era.