For over four centuries the headquarters of the agate industry has been in the valley be tween Idar and Oberstein, some 40 miles from Bingen on the Rhine. There are probably 150 agate mills working an average of three to five stones each in this little valley. These are chiefly operated by water-wheels 10 to 18 feet in diameter, abundant power being secured from the rapid mountain streams of the neigh borhood. The millstones are of red sandstone, each about five feet in diameter, and rotate in a vertical plane, making about three revolutions per second. The workmen lie stretched in an almost horizontal position upon a low wooden grinding stool fitted to the chest and abdomen, leaving the limbs free. The hands are engaged in holding and grinding the agate, while the feet are firmly pressed against short stakes screwed into the floor, the reaction enabling the grinder to press the agate with much force against the moving millstone. During the process the agates glow most beautifully with a bright red phosphorescence. After having been ground the agates are polished with tripoh on cylinders of wood or a metal disc. Consult Popular Science Review, New Series, Vol I, p. 23.
Moss-agate or aMocha-stoties is a variety of chalcedony through which are scattered black or brown masses, more or less resembling moss. These impurities are usually one of the man ganese oxides. In the Chinese moss-agate they appear as thin matted filaments of a green color, which are often artificially colored.
Beautiful dendrites are sometimes found in chalcedony. The name dendritic-agate or tree agate is given to these highly prized forms. Moss-agates abound at many localities in the United States, especially in Wyoming.
In the emelaphyrea of the hills around Idar, agates of considerable beauty are found. For merly they were extensively quarried there, but since 1827 the lapidaries of Idar have secured their supplies largely from Uruguay and Brazil, which countries have long furnished nearly the entire commercial supply, though Scotch agates are marketed to some extent. Small banded agates of much beauty abound on the shores of Lake Superior; large and fine specimens occur plentifully in western Texas. Agates abound in many other regions, while very many localities yield choice agates sparingly. Most of the pol ished agate specimens and novelties of the tour ist resorts, though often purporting to be of local origin, come from Brazil or Uruguay and are polished in Germany.
Agate is used in making burnishers and agate mortars and pestles and, owing to its hardness., for the knife edges of balances. It is worked up as a decorative stone into vases, dishes, ash trays, paper weights, paper cutters, etc., and is mounted as a semi-precious stone in a great variety of objects, such as jewel boxes, glove or shoe buttoners, watch charms, letter openers and scarf pins. Every boy is familiar with agate marbles, but the cheaper grades of these are .only glass. From the earliest times the black and white banded agates (see Onyx) and the red and white (see SARDONYX) have been used for seal rings and for carving cameos. The ancients also regarded agate as a charm against the intoxication of love. Consult Ruskin, 'On Banded and Brecciated Concre tions> (in Geological Magazine, 1867 to 1870) 'Ethics of Dust,' p 190; 'The Vale of Idar,> by S. Weisse (in Blackwood's Magazine, Vol. cxlviii, pp. 75 and 208).