I would cut off at least 1/2 inch from each end and throw it away. The surface cracks are visible in the picture and they will be all over the face and judging by the discoloration of these little cracks, they are apt to be very deep.
The ivory near the large cracks is also unuseable.
To check for cracks you can't see you can spread some liquid dye or ink, then clean offe the surface down to the ivory. The cracks will show the dye.
Whenever you cut ivory pieces you need to seal the end grain. Use 5 minute or melted wax or something else, but do it ASAP. On a cue, the ivory ferrules are sealed with a tip or the shaft.
Glad you didn't pay much.