Underground Treasures: How and Where to Find Them / A Key for the Ready Determination of All the Useful Minerals Within the United States

by James Orton

1.—Agate.

THIS stone is a mixture of several kinds of quartz, mainly the white, red, brown and black, disposed in layers or clouds. The layers are zigzag, circular or in straight bands (onyx). Occurs in irregular rounded masses; not very translucent; not altered by heat or acids; cannot be cut with a knife nor split into plates; takes a high polish; lustre glassy; gravity 2.5.

Value.—Used for jewelry and ornamental work, mortars, vases, knife-handles, burnishers, etc. The colors are deepened by boiling in oil and then in sulphuric acid.

Localities.—Found in granite and trap regions, generally by the shores of rivers, lakes and the sea; as, north-west shore of Lake Superior; Missouri, Columbia, Colorado and Connecticut Rivers; Crescent City, Cal.; Hancock County, Ga.; near Tampa Bay, Fla.; Fulton, Penn.; Yellowstone Lake, Wy.[3]