Gingernuts

Starting with an organic mesh of fibres (cartilliage), my body can produce a strong, flexible and highly rigid ceramic structure from calcium phosphate (bone). I'd like to engineer plants to make similar structures but with stronger, engineering grade ceramics (like maybe Al2O3 or SiC) so I can grow my own cities. Try as I might, this is actually really hard to look up; upon reference to a few biochemistry books and a precursory googling, I can't seem to find very much on the biochemistry of ossification at all (bone formation). I know it isn't quite a diffusive process, though perhaps it is like crystal formation in a solution or something, but ultimately I'm stuck - is there an enzyme or something that facilitates this? Thanks guys