28.—Emery.
Occurs in granular masses, sometimes with bluish crystals; looks like fine grained iron ore; breaks with uneven surface; scratches quartz easily; very tough; brittle; gravity 4.
Value.—Used extensively as a cutting and polishing material.
Localities.—Found generally in limestone or granite with Magnetic Iron Ore. Chester, Mass.; Newlin and Unionville, Penn.; Macon and Guilford Counties, N. C.