SRD:Stone of Weight
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Stone of Weight (Loadstone): This stone appears to be a dark, smoothly polished stone. It reduces the possessor’s base land speed to one-half of normal. Once picked up, the stone cannot be disposed of by any nonmagical means—if it is thrown away or smashed, it reappears somewhere on his person. If a remove curse spell is cast upon a loadstone, the item may be discarded normally and no longer haunts the individual.