DEPARTMENT OF GEOLOGY 47 
Japan is represented by a series of polished marble spheres 
of various sizes. 
A series of marbles from Africa and Asia includes the well 
known ivory-colored Numidian marbles. 
A series of travertines including some large polished speci- 
mens comprises the varieties commonly known as Mexican onyx, 
onyx marble and stalagmite marble. The clear translucent 
specimens represent the material as originally deposited. The 
opaque red-brown effects are produced where air has had long 
access to the material in the ground and has caused an oxida- 
tion of the iron contained in the material. 
Serpentines. Next to marble the green or red serpentines 
are perhaps the most generally used of ornamental stones. A 
good series is shown. Especially noteworthy are the curiously 
mottled red and dark green serpentines from. Lizard Point, Corn- 
wall, and the dark colored variety from Saxony which is turned 
on a lathe to form various ornamental objects. All of these green 
serpentines are now commonly known as verde antique, although 
the name was formerly applied only to those of the shade of green 
possessed by the Greek specimen, E 504. The ophite from New 
York is a granular mixture of calcite and serpentine. 
A number of slabs of granite and eruptive rocks are shown. 
Owing to their hardness and the consequent expense of working, 
these stones are not so frequently polished as the marbles, but, 
as illustrated by these specimens, when polished they often 
present very beautiful effects. 
A systematic collection of common building stones is also 
exhibited in the form of four-inch cubes showing different kinds 
of finish on different faces. The series is classified according to 
the commercial groups of limestones, marbles, slates, sand- 
stones and granites, and into the nearest of these classes are 
placed such building stones as lava, diorite, conglomerate, etc., 
which do not strictly belong to either. Foreign building stones 
constitute a separate collection. 
Building stones of Mexico and Ecuador also are grouped as a 
separate series. These are mostly volcanic rocks, lavas, and 
tuffs, which are sufficiently durable for mild climates and yet 
soft enough to be easily worked with simple tools. The build- 
ing stones from Ecuador are ordinary pumice stone. Other 
foreign building stones form a separate series of four-inch cubes 
representing principally English and Spanish localities. 
