emery(n = noun.substance) - a hard grey-black mineral consisting of corundum and either hematite or magnetite; used as an abrasive (especially as a coating on paper);
is a kind of mineral

   Corundum in the form of grains or powder, used in the arts for grinding and polishing hard substances. Native emery is mixed with more or less magnetic iron. See the Note under Corundum. [1913 Webster]

emery, n.
1 a coarse rock of corundum and magnetite or haematite used for polishing metal or other hard materials.
2 (attrib.) covered with emery.

Idiom:
emery-board a strip of thin wood or board coated with emery or another abrasive, used as a nail-file. emery-paper cloth or paper covered with emery, used for polishing or cleaning metals etc.

Etymology:
F {eacute}meri(l) f. It. smeriglio ult. f. Gk smuris, smeris polishing powder

N  sharpness, acuity, acumination, spinosity, point, spike, spine, spicule, spiculum, needle, hypodermic needle, tack, nail, pin, prick, prickle, spur, rowel, barb, spit, cusp, horn, antler, snag, tag thorn, bristle, Adam's needle, bear grass, tine, yucca, nib, tooth, tusk, spoke, cog, ratchet, crag, crest, arete, cone peak, sugar loaf, pike, aiguille, spire, pyramid, steeple, beard, chevaux de frise, porcupine, hedgehog, brier, bramble, thistle, comb, awn, beggar's lice, bur, burr, catchweed, cleavers, clivers, goose, grass, hairif, hariff, flax comb, hackle, hatchel, heckle, wedge, knife edge, cutting edge, blade, edge tool, cutlery, knife, penknife, whittle, razor, razor blade, safety razor, straight razor, electric razor, scalpel, bistoury, lancet, plowshare, coulter, colter, hatchet, ax, pickax, mattock, pick, adze, gill, billhook, cleaver, cutter, scythe, sickle, scissors, shears, pruning shears, cutters, wire cutters, nail clipper, paper cutter, sword, bodkin, belduque, bowie knife, paring knife, bushwhacker, drawing knife, drawing shave, microtome, chisel, screwdriver blade, flint blade, guillotine, sharpener, hone, strop, grindstone, whetstone, novaculite, steel, emery, sharp, keen, acute, acicular, aciform, aculeated, acuminated, pointed, tapering, conical, pyramidal, mucronate, mucronated, spindle shaped, needle shaped, spiked, spiky, ensiform, peaked, salient, cusped, cuspidate, cuspidated, cornute, cornuted, cornicultate, prickly, spiny, spinous, spicular, thorny, bristling, muricated, pectinated, studded, thistly, briary, craggy, snaggy, digitated, two-edged, fusiform, dentiform, denticulated, toothed, odontoid, starlike, stellated, stelliform, sagittate, sagittiform, arrowheaded, arrowy, barbed, spurred, acinaciform, apiculate, apiculated, aristate, awned, awny, bearded, calamiform, cone-shaped, coniform, crestate, echinate, gladiate, lanceolate, lanciform, awl, awl-shaped, lance-shaped, awl- shaped, scimitar-shaped, sword-shaped, setarious, spinuliferous, subulate, tetrahedral, xiphoid, cutting, sharp edged, knife edged, sharp as a razor, keen as a razor, sharp as a needle, sharp as a tack, sharpened, set.

emery cloth, emery paper, emery rock, emery stone, emery wheel