THE ONYX MARBLES. 563 



all sliades. This oxidation has naturally followed along the lines of 

 jointing" and penetrated the more porous layers, so that what were once 

 large blocks of homogeneous green are now surrounded by a crust of 

 varying thickness of the oxidation product. All stages of the process 

 are seen at the various openings, from those in which the green stone 

 is covered with a mere crust, and scarcely sufficiently veined to give a 

 desired variety, to those in which scarcely a trace of the original green 

 remains, but the whole block is of a red brown color in varying shades. 

 At times the oxidation has been accompanied with a removal of so 

 large a proportion of the lime carbonate that the texture is destroyed; 

 the stone becomes somewhat cellular or spongy, and does not acquire 

 a good surface and polish. In other cases, the stone still retains its 

 compact structm e and susceptibility to a high polish, though necessa- 

 rily it loses its transluceucy and becomes quite opaque. Nevertheless, 

 the stone is by no means undesirable for either furniture toppings or 

 for decorative purposes. The colors are rich but not gaudy, and, when 

 properly prepared, are capable of effects both unique and beautiful. 

 There is in the National Museum a slab of the oxidized stone ((30845) of 

 brown and red color so cut with the grain as to resemble in a wonder- 

 ful degree a piece of antique tapestry, (pi. 15.) The details of its 

 structure are intricate in the extreme, and since what is to be seen by 

 a careful study of them depends almost wholly on the vividness of 

 one's imagination, the writer drops the subject to be taken up, it may be, 

 by those more gifted, either in imagination or in the faculty of expres- 

 sion. This type of onyx, I may say, differs from anything 1 have seen 

 elsewhere, and, while the present workers regard it as valueless, and it 

 is doubtful if the quarries can be relied upon to produce any large 

 supply, or even two blocks alike, I still regard it as a beautiful stone, 

 and one well worthy of consideration. In certain of the outcrops no 

 green at all appears, but the stone lies in somewhat wavy layers of 

 from 1 or 2 to 12 or 15 inches in thickness, and which are traversed by 

 narrow alternating bands of brown, white, yellow, and sometimes pink. 

 This variety of onyx is more granular in structure— due to coarse crys- 

 tallization—than the green onyx, less translucent, and, on the whole, 

 much less desirable. It is, nevertheless, a tine marble. Owing to the 

 wavy nature of the bands, they appear and disappear in the form of 

 veins, blotches, streaks, and clouds of varying intensity in color when 

 the stone is sawn into slabs. The compact, highly lustrous green stone, 

 with a surface almost as close as enamel, and with its veins and dashes 

 of red and brown, is, however, the most desirable of all. 



The so-called Cave Creek quarries of Arizona are also in Yavapai 

 County, but in the extreme soutliern part, near the Mariposa County 

 line. At present they are accessible only from Phoenix, and over a 

 road the latter 12 to 20 miles of which is hilly in the extreme. In 

 riding over it one can but be reminded of a saying in reference to 

 the Territory to the effect that "If Arizona 'd been laid flat it would be 

 bigger'u any two States in the Union." But to reach the market the 



