The invention relates to a material that can be used as a bone substitute and to a method for the preparation thereof. The material comprises an organic phase (I) comprising striated collagen fibrils constituted of collagen I triple helices, said fibrils being organized over a large distance according to a 3D geometry associating aligned domains and cholesteric domains, and also isotropic domains where they are not organized； and a mineral phase (II) comprising apatite crystals having a hexagonal crystalline structure, space group 6/m, comprising at least calcium ions and phosphate ions； the axis c of said apatite crystals of the mineral phase is coaligned with the longitudinal axis of the striated collagen fibrils of the organic phase and the collagen content in the material is at least 75 mg/cm3. The method for preparing the material comprises preparing an initial acidic aqueous solution of collagen which is a precursor for the organic phase (I), and at least one aqueous solution of precursors for the mineral phase (II) and precipitating the collagen by increasing the pH to a value of at least 7. According to this method: the concentration of collagen in the acidic aqueous solution is at least 75 mg/ml and remains constant during said increase in pH； the mineral phase precursors comprise at least one calcium salt and at least one phosphate salt； the precipitation of the mineral phase (II) is carried out by bringing the mineral phase precursor solution into contact with the organic phase (I), said bringing into contact being carried out before or after the precipitation of said organic phase (I).
