Bone is actually 5x harder than steel because even though hydroxyapatite has a mohs hardness of 5 the calcium strengthens and hardens the mineral making bone harder up to the mohs hardness scale of I should say between 6.5 to 7 slightly harder than steel which is 5.5 to 6. Though bones being slightly harder on mohs hardness scale by a few points would mean it is 2 to 5 TIMES HARDER though the only thing wrong is its so hard that it is brittle ^_^ which you could make up by impact training such as martial arts to make your bones thicker to be less prone to breaking
