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.
Localities.—Found in limestone with Garnet and Zincite. Hamburg and Stirling Hill, N. J.
31.—Galena.
Occurs in crystals and masses; brilliant lustre; brittle; easily broken; powder, when finely rubbed is black; can be cut with a knife; heated it gives off sulphur and melts; dissolves in nitric acid leaving a white powder at the bottom; gravity 7.5—or a little heavier than cast-iron.