A particularly preferred grinding medium is {HEAD ~ a material} commercially available under {TAIL ~ the name} YTZ Ceramic Beads, commercially available from S. E. Firestone Associates 
commercially available under
A particularly preferred grinding medium is { HEAD ~ a material } commercially available under { TAIL ~ the name } YTZ Ceramic Beads , commercially available from S. E. Firestone Associates
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH