Abstract: A monolithic single crystal Si rate-gyro consisting of in the preferred embodiment, an outer torsional frame, self resonating with a substantial amplitude, as controlled by a four-terminal piezo torsion sensor, connected to an inner frame by torsional hinges. The inner frame itself is connected to a fixed inner post, by a set of torsion hinges, defining an axis of rotation perpendicular to the first axis. Rotation of the axis of oscillation of the outer body causes the moving mass and the inner frame to tilt and oscillate at the outer frequency due to Coriolis forces, thereby periodically deforming the inner hinges in torsion. These inner hinges are likewise equipped with a four-terminal piezo voltage torsion sensor, giving an indication of the rate of rotation of the sensor. The design allows for good sensitivity, due to the substantial swing of the outer oscillator, its high moment of inertia, excellent Si spring characteristics, and excellent sensitivity of the torsional sensors.