51 
appear in the collection from foreign localities, do not exist in the 
United States. Deposits are known but for various reasons re- 
main unworked. 
Cases 8 and 9. — Marbles and gypsums, Great Britain and 
Japan. The best known of these is the encrinal marble of Devon, 
England. 
The spheres are manufactured in Japan and exported as 
curiosities. 
Case 10. — Granites and eruptive rocks. 
Owing to their hardness and the consequent expense of work- 
ing, these stones are not so frequently polished as the marbles, 
but, as illustrated by these specimens, when polished they often 
present very beautiful effects. 
HALL 68. 
BUILDING STONES, 
This Hall contains a systematic collection of building stones. 
Case 1. — Foreign building stones. Roofing slate. 
Case 2. — Limestones and marbles. Four-inch cubes of many 
of the limestones and marbles of the United vStates used for build- 
ing. 
Case 3, — Sandstones. Four-inch cubes of many of the sand- 
stones of the United States used for building purposes. 
Case 4. — Granites. Four-inch cubes of many of the granites 
of the United States used for building purposes. The above four 
kinds of rock constitute nearly all the valuable building stones 
used in temperate climates. 
Case 5. — Building stones of Mexico and Ecuador. 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 building stones from Ecuador are ordi- 
nary pumice-stone. 
Case 6, — Cubes of granite, showing^ the various ways in 
which the rock may be dressed. 
Platform 7, — Slate, Wales. These specimens illustrate the 
manner in which blocks of slate are split or cleaved into a series 
