title: Calcium ferrocyanide
text: # Calcium ferrocyanide
  
  Calcium ferrocyanide is an inorganic compound with the formula $Ca_2[Fe(CN)_6].$ It is the $Ca^{2+}$ salt of $[Fe(CN)_6]^{4-},$ ferrocyanide complex ion. A yellow solid, it is used as a precursor to the pigment Prussian blue.
  
  ## Safety
  
  It was listed in 2012 by the EU as a "Food Improvement Agent".
  
  In the EU, ferrocyanides (E 535–538) were, as of 2018, solely authorised in two food categories as salt substitutes. Kidneys are the organ for ferrocyanide toxicity.
  
  