ELASTIC CONSTANTS OF ROCKS- 29 
A square prism of the marble was employed in measuring the elastic con- 
stants, and the detailed results are given in the accompanying table, and arc 
represented in graphic form in figure 8. I represents longitudinal compres- 
sion and II lateral extension. 
The following are the values obtained : 
E = 7592,ooo; <r= 0.263; D= 5, 341,000; C= 3,000,000 
7000 
1000 
80 120 160 200 ^40 
STRAIN 
40 
FIG. 8. Vermont marble. Stress-strain curves. 
MARBLE), TENNESSEE, UNITED STATES. 
This is a marble known in trade as " Pink Tennessee, " and is largely 
used for decorative work. It has a brownish pink color and when polished 
shows a somewhat mottled surface. 
Under the microscope it is seen to consist of rather large irregular-shaped 
and often distinctly rounded individuals of calcite, which are fitted closely 
together along sharp and in some cases crenulated lines. These individuals 
are almost invariably traversed by narrow lamellae, due to polysynthetic 
twinning, and are occasionally twisted, so that they show an undulatory ex- 
tinction. Between these large calcite individuals there are frequently present 
masses of what is apparently a tabulate coral, showing sheaves of tubes which 
in cross section are approximately circular in outline. The calcite individ- 
uals are often embedded in this coralline material, as if they had been 
developed by its recrystallizatiori ; in other cases, however, their appearance 
suggests a derivation from crinoidal fragments. All the tubes of the coral, as 
well as the interspaces of the tubes, if any existed, are now filled with calcite, 
so that the substance of the rock is continuous, resulting in a compact marble. 
Fragments of the rock dissolve readily in cold dilute hydrochloric acid, leaving 
only a very trifling residue, which has the color of the rock itself. 
A color-process photograph of a polished surface of the rock is shown in 
Plate IV A, and a photomicrograph of a thin section of the rock, taken in ordi- 
nary light and magnified 27 diameters, is shown in Plate IV B. In this 
photomicrograph a fragment of the coralline material is seen in the center 
of the field, while the border is formed chiefly of individual calcite grains. 
