CLINKSTONE, called also phonolite, a felspathic rock of the trap family, usually fissile.
"Principles of Geology" by Charles Lyell
As both trachyte and basalt pass into clinkstone, the rock so called must be very various in composition.
"A Manual of Elementary Geology" by Charles Lyell
Some varieties are slaty, and are frequently mistaken for clinkstone, which they closely resemble.
"Geology" by James Geikie