The present invention provides an artificial bone graft implant formed of a biocompatible mineral material which possesses compressive strength similar to that of natural bone and allows bone tissue ingrowth for permanent fixations. The artificial bone graft implant is used as a replacement for living bone material in surgical procedures requiring the use of bone graft material. The inventive implant has a body configured to be implanted into a prepared site in a patient's bone tissue, with the body having a pair of opposed outer surfaces defining the body. A first and a second porous portion form the body with the first and second porous portions having pores of different sizes such that the average pore size of the first porous portion is greater than the average pore size of the second porous portion. The first porous portion of the body is formed in the shape of a core, with the core being in contact with the opposed outer surfaces of the body, and the second porous portion of the body is formed in the shape of an outer shell. The pore size of the first porous portion of the implant allows for the ingrowth of bone tissue while the pore size of the second portion of the implant allows for a load bearing capacity similar to natural bone.