Abstract: A suspension for the ultrasonic preparation of natural hard tissue contains between 5 and 45 wt. % of hard particles, between 2 and 40 wt. % of at least one polyhydric alcohol and between 0.1 and 10 wt. % of dispersants and thickeners The suspension having this composition is capable of being stored and shipped without the risk of the hard particles settling. It constitutes a pumpable concentrate which, during the actual ultrasonic preparation, is diluted with an appropriate amount of water to give the ready-to-use suspension.