Name of Substance.

Resistance to

Crushing in

Pounds per

Sq. In.

Basalt....................

18,000-27,000

Brick, soft..................

300-1,500

" hard................

1,500-5,000

" vitrified...................

9,000-26,000

Granite.................

17,000-26,000

Limestone.................

4,000-9,000

Marble...................

9,000-22,000

Sandstone.........................

4,500-8,000

Slate.....................

11,000-30,000