A sort of composite material can be produced from a single kind of natural organic fiber. This has been observed with bovine leather. During the formation process in a die particulated leather fibers were subjected for a period of about 6 min to a pressure of over 100 bar at a processing temperature of between 60 and 200 °C. In this way a portion of these collagenous fibers was plastically deformed and converted into continuous matrix material in which unconverted fibers act as matrix reinforcement. Round, collagenous fibers assumed an angular cross section and became the building blocks of the continuous matrix. This is clearly visible on pictures made with a scanning electron microscope. At a processing temperature of 70 °C and a pressure of 650 bar, applied for 6 min, the maximum compression strength at room temperature is found to be 185 MPa. At these processing parameters Young's modulus is about 2.4 GPa and the bulk density is 1350 kg/m3. Other natural fibers, to be used as organic raw material for the production of composites, are currently under investigation.