The reaction conditions are critical to the process and determine the particle size.Iron(II) carbonate can also be thermally decomposed into Iron(II,III):
3FeCO3 → Fe3O4 + 2CO2 + CO

Reactions
Reduction of magnetite ore by CO in a blast furnace is used to produce iron as part of steel production process:

  
    
      
        
          
            
              Fe
              
                3
              
              
                
              
            
            
              O
              
                4
              
              
                
              
            
          
          +
          4
          
          CO
          ⟶
          
            3
            
            Fe
          
          +
          4
          
          
            CO
            
              2
            
            
              
            
          
        
      
    
    {\displaystyle {\ce {{Fe3O4}+ 4CO -> {3Fe}+ 4CO2}}}
  Controlled oxidation of Fe3O4 is used to produce brown pigment quality γ-Fe2O3 (maghemite):

  
    
      
        
          
            
              
                
                  2
                  
                  
                    Fe
                    
                      3
                    
                    
                      
                    
                  
                  
                    O
                    
                      4
                    
                    
                      
                    
                  
                
                ⏟
              
            
            
              magnetite
            
            
              
            
          
          +
          
            
              
                1
                2
              
            
            
              O
              
                2
              
              
                
              
            
          
          ⟶
        
         
        
          
            
              
                
                  
                    
                      3
                      
                      
                        (
                        γ
                        
                          −
                        
                        
                          Fe
                          
                            2
                          
                          
                            
                          
                        
                        
                          O
                          
                            3
                          
                          
                            
                          
                        
                        )
                      
                    
                    ⏟
                  
                
                
                  maghemite
                
                
                  
                
              
            
          
        
      
    
    {\displaystyle {\ce {\underbrace{2Fe3O4}_{magnetite}+ {1/2O2}->}}\ {\color {Brown}{\ce {\underbrace{3(\gamma-Fe2O3)}_{maghemite}}}}}
  More vigorous calcining (roasting in air) gives red pigment quality α-Fe2O3 (hematite):

  
    
      
        
          
            
              
                
                  2
                  
                  
                    Fe
                    
                      3
                    
                    
                      
                    
                  
                  
                    O
                    
                      4
                    
                    
                      
                    
                  
                
                ⏟
              
            
            
              magnetite
            
            
              
            
          
          +
          
            
              
                1
                2
              
            
            
              O
              
                2
              
              
                
              
            
          
          ⟶
        
         
        
          
            
              
                
                  
                    
                      3
                      
                      
                        (
                        α
                        
                          −
                        
                        
                          Fe
                          
                            2
                          
                          
                            
                          
                        
                        
                          O
                          
                            3
                          
                          
                            
                          
                        
                        )
                      
                    
                    ⏟
                  
                
                
                  hematite
                
                
                  
                
              
            
          
        
      
    
    {\displaystyle {\ce {\underbrace{2Fe3O4}_{magnetite}+ {1/2O2}->}}\ {\color {BrickRed}{\ce {\underbrace{3(\alpha-Fe2O3)}_{hematite}}}}}

Structure
Fe3O4 has a cubic inverse spinel group structure which consists of a cubic close packed array of oxide ions where all of the Fe2+ ions occupy half of the octahedral sites and the Fe3+ are split evenly across the remaining octahedral sites and the tetrahedral sites.
Cranioschisis (Greek: κρανιον kranion, "skull", and σχίσις schisis, "split"), or dysraphism, is a neural tube defect involving the skull. In this defect, the cranium fails to close completely (especially at the occipital region). Thus, the brain is exposed to the amnios and eventually degenerates, causing anencephaly.Craniorachischisis is on the extreme end of the dysraphism spectrum, wherein the entire length of the neural tube fails to close. See also
Rachischisis
Spina bifida


== References ==