Bio essen

Me and my girl were recently discussing the German penchant for biological food stuffs---what we call "organic food" in my country. The terminology strikes me as a little strange, since it suggests that if we weren't eating bio-food we would normally be eating inorganic substances. According to Wikipedia, an inorganic substance is any compound not involving carbon---except certain carbonates, simple oxides of carbon and cyanides, as well as the allotropes of carbon. I am trying to think of how many inorganic materials out there that we humans can really ingest. My list so far is: water, salt (sodium chloride), and potassium chloride. In addition there are some substances which are probably OK to swallow but indigestable: elemental carbon, glass, various pure metals and semimetals. This list is probably longer. Do any of my loyal readers have any other substances to add to the list?

Update: The list should include MgSO_4 according to Sveti. I wonder how it tastes? Other comments were not as helpful.