The invention relates to a preparation for a magnesium ammonium phosphate cement. There is provided a preparation comprising (a) a magnesium calcium phosphate of the formula MgxCay(PO4)2Oz, wherein x+y@4, x>1, y>0, z=x+y-3 and z>=0 (b) an ammonium salt and (c) water wherein the ammonium salt and the water can be present partially or completely as an aqueous solution of the ammonium salt.