526 THE POPULAR SCIENCE MONTHLY. 



quence 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, trav- 

 ersed 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 alabas- 

 ter" (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 commer- 

 cial 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 pres- 

 ent 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 frag- 

 ments, 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 chem- 

 ical 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 Coun- 

 ty, New York ; and Dublin, Harford County, Maryland. The Ver- 

 mont 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 text- 

 ure, 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 



