THE ONYX MARBLES. 565 



there are two openings or outcroppings, some half a mile apart, 

 lying in sections 9 and 16 of township 31 sonth, range 15 east, INIount 

 Diablo meridian. The inclosing rock is a slaty sandstone, the ledges 

 standing nearly on edge and having a thickness of about 10 feet. The 

 outcroppings lie one on the northern slope of the ridge and the other 

 on the southern, the hill rising about 80 feet between them. Whether 

 the two are parts of the same vein or bed is as yet unknown. The 

 strike of the more northern croppings is directly toward the southern, 

 though that of the southern is diagonal to the course of the others. 

 The stone is very close in texture, acquires a high lustrous polish, and 

 shows when cut across the grain a beautiful wood-like banding. The 

 colors are quite variable, but not so pronounced as those ot Arizona. 

 White, translucent, with a pearly luster, is the prevailing type, but 

 pinkish and purple shades, with tinges of blue, orange, red, and olive, 

 are not uncommon, the colors being sometimes in blotches and some- 

 times in veins. A peculiar translucent, smoky variety is not uncommon, 

 resembling some varieties of true alabaster. A pair of columns pre- 

 pared some time ago excited considerable admiration from showing two 

 apparent geode-like cavities lined with crystals of burnished gold set 

 in a dark olive and purple ground. In reality no cavities existed, the 

 stone being solid and sound throughout. 



One of the most remarkable and uniqne varieties, but which occurs 

 only sporadically, is of a translucent white, but so injected jiarallel 

 with the bedding with argillaceous matter as to give most wonderful 

 cloud-like effects, such as words can not satisfactorily describe. Vis- 

 itors to the California pavilion at the World's Columbian Exposition 

 at Chicago in 1893 will recall the unique pictures in stone there displayed 

 by the Kesseler Brothers, of San Francisco. In some slabs the dark 

 coloring matter was so distributed as to give the effects of jjrecipitous 

 mountains, with tops in the clouds and lakes and valleys at their feet. 

 In others the effect was as if the surface were roughly mammillated with 

 smoky clouds of varying degrees of density. In all these forms the slabs 

 must be cut moderately thin and parallel to the bedding and viewed by 

 transmitted light in order to bring out the best effects. (PI. 12.) The 

 coloring matter in these cases was found to be mechanically included 

 clay, which remained as a muddy sediment in the bottom of the beaker 

 when the stone was dissolved in hydrochloric acid, as already noted. 



It is stated in the report above referred to that the stone could 

 be taken out in blocks 10 feet square (thickness not stated) with- 

 out a flaw. The material is hauled by wagon from the quarries to 

 Musick, and shii^ped thenc^e by rail to San Francisco, where it is 

 worked up. Active and systematic quarrying was begun here in the 

 summer of 1890. 



Several years ago a resinous travertine occurring as superficial 

 deposits on a bare hillside near Suisun City, in Solano County ,wa8 

 worked somewhat spasmodically, but was soon abandoned, owing in part, 

 it is said, to the damage done by injudicious blasting. It is probable, 



