Page:Popular Science Monthly Volume 27.djvu/544

526 are now produced east of the Rocky Mountains, though several States are known to contain material that might be thus utilized if put upon the market. California, however, produces two varieties worthy of especial notice. The one is a white, finely crystalline stone, traversed by a network of fine dark lines, in general appearance very much like the celebrated bardiglio marble from the Serravezza quarries, but that the ground-mass is lighter in color. The second variety is the beautiful stalagmite marble, or so-called onyx, from quarries at San Luis Obispo. This stone is pearly white in color, translucent, and traversed by fine, wavy, parallel lines, like the lines of growth upon the trunk of a tree. It takes a beautiful polish, and is quite extensively used for small stands and ornaments of various kinds. Excepting in the matter of color it is identical with the celebrated "Oriental alabaster" (wrongly so called), from Blad Recam, near the Ravine of Oned Abdallah, Egypt, this last being of a yellowish or amber hue. The San Luis Obispo rock is the only stalagmite marble of any commercial importance at present found in this country, though a beautiful variety, known as "Mexican onyx," is quarried at Tecali, State of Puebla, Mexico.

In the way of true conglomerate or breccia marble there is at present nothing quarried, though a beautiful variety occurs in inexhaustible quantities near Frederickton, Maryland, and in other parts of this State and Pennsylvania. The stone consists of rounded and angular fragments, of varying colors and all sizes up to several inches in diameter, of quartz and limestone imbedded in a fine gray ground-mass. This admixture of hard and soft material renders the dressing of the stone a matter of great difficulty, since the flinty pebbles break away from the softer ground-mass in the process of cutting. The large pillars of the old House of Representatives in the Capitol at Washington are of this stone.

The rock serpentine, though differing entirely from marble in chemical composition, is used for similar purposes, and may be mentioned here. The three principal sources of this rock, or of serpentine in combination with calcite, are Roxbury, Vermont; Moriah, Essex County, New York; and Dublin, Harford County, Maryland. The Vermont stone is deep green in color, and traversed by white veins of calcite. It takes a beautiful polish, and compares very favorably with the Italian verde antique or verde di Prato from quarries in Tuscany. The Moriah stone is similar in color, but granular in texture, and spotted, rather than veined. At present it is found in the market in the form of mantels, table-tops, monuments, etc. The Maryland stone is more uniformly green in color than either of those mentioned above, containing very little calcareous matter. It is said to occur in almost inexhaustible quantities and within easy reach of the Baltimore market, but for some unexplained reason little, if any, of it is now in use. A coarse serpentine used for general building