VALUE.--If of a fine yellow hue, it is a valuable copper ore (yielding from twelve to forty per cent.) and source of blue vitriol. LOCALITIES.--Found in mountainous or granite regions with other ores. Lubec and Dexter, Me.; Franconia, Unity, Warren, Eaton, Lyme, Haverhill and Shelburne, N. H.; Corinth, Waterbury and Strafford, Vt.; Southampton, Turner’s Falls, Hatfield and Sterling, Mass.; Bristol and Middletown, Conn.; Ancram, Rossie, Wurtzboro’ and Ellenville, N. Y.; Phœnixville and Pottstown, Pa.; Bare Hills, Catoctin Mountains, near Newmarket and Finksbury, Md.; Phœnix and Walton Mines, Va.; Greensboro, Charlotte and Phœnix Mines, N. C.; Hiwassee Mines, Tenn; Cherokee, Rabun and Habersham Counties, Ga.; Presque Island, Lake Superior; Mineral Point, Wis.; Union, Keystone, Empire and other mines, Calaveras County, La Victoire and Haskell claims in Mariposa County, Amador and Plumas Counties, Cal.; near Virginia City, Mont. [Illustration: PROSPECTING DIAMOND DRILL.] 27.--DIAMOND. Occurs in crystals and irregular angular masses; cannot be scratched by any other mineral or the file; brilliant lustre; feels cold to the touch; when rubbed on the sleeve exhibits electricity for hours; retains the breath but a short time; often tinged yellow, red, or green; gravity 3.5. VALUE.--Used for jewelry, lenses and for cutting glass. LOCALITIES.--Found in gold-regions, in river-washings of sand and pebbles; usually with coarse gold, but deeper down. Rutherford, Cabarras, Franklin and Lincoln Counties, N. C.; Hall County, Ga.; Manchester, Va.; Cherokee Ravine, N. San Juan, French Canal, Forrest Hill, Placerville and Fiddletown, Cal. 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. 29.--FLUOR SPAR. Occurs in square crystals and in masses; glassy lustre; powder white; brittle; crackles when heated and then shines in the dark; does not effervesce with acids; is not scratched by marble; gravity 3. VALUE.--Used as flux in glass and iron works. LOCALITIES.--Found in limestone, granite, slate, etc., often at lead-mines. Blue Hill Bay, Me.; Westmoreland, N. H.; Putney, Vt.; Southampton, Mass.; Trumbull, Plymouth, Middletown and Willimantic, Conn.; Muscolonge Lake, Rossie and Johnsburg, N. Y.; near Franklin, N. J.; near Woodstock and Shepardstown, Va.; Smith County, Tenn.; Mercer County, Ky.; Gallatin County, along the Ohio, Ill. Castle Dome District, Ariz. 30.--FRANKLINITE. Occurs crystallized and in masses; generally made of coarse grains; brittle; powder dark reddish-brown; heated with soda turns bluish-green; dissolves in muriatic acid; gravity 5. VALUE.--An ore of zinc.