in volcanic regions, and is common in the hills about Rome. It often
contains the moulds left by leaves and other materials incorporated in
the deposit. These account for the corrugations of the stone when it is
cut. In California, as in other regions where hot springs are found,
travertine is not uncommon. It is found notably in the volcanic district
of Mono County, and elsewhere, sometimes in the form of Mexican onyx,
which is only a translucent variety of the same marble. In its
reproduction here the marble has been imitated even to the natural
imperfections which roughened the Italian stone. In the concave surfaces
of the ornamentation the color has been deepened, so that it appears
sometimes as a rich reddish brown. All this enhances the antique effect,
making the palace walls and columns still more like those of the old
Roman construction.

Besides the travertine the eight other colors employed are:

1. French Green, used in all lattices, flower tubs, curbing of great
plats, where it complements the green of the grass, In the exterior
woodwork and some of the smaller doors.

2. Oxidized Copper Green, a peculiar mottled light green. All the domes,
except the six yellow ones in the Court of the Universe, are of this
light green. It forms a sharp contrast with the blue sky and a pleasing
topping to the travertine walls.

3. Blue Green, found in the ornamentation of the travertine, and in the
darker shades at the bases of the flag poles. These first three colors,
all in tones of green, are regarded as one unit in the spectrum of nine
colors allowed by Guerin.