1. A marking device for identifying a subcutaneous biopsy cavity comprising: a first nonabsorbable marker element detectable by a first imaging modality, which is a radiographic imaging modality; and a second nonabsorbable marker element detectable by a second imaging modality, which is ultrasonography, but not detectable by said first imaging modality, wherein the second marker element extends generally along an axis and the first marker element is radiopaque, encircles a portion of the second marker element, and lies in a plane that is generally perpendicular to the axis of the second marker element.