The wall rocks have undergone a "propylitic" alteration, with development of chlorite, Epidote, and probably sericite, much as at Butte.
"The Economic Aspect of Geology"
C. K. Leith
Here is nobly born quartz living with a green mineral, called Epidote; and they are immense friends.
"The Ethics of the Dust"
John Ruskin
He lets the pale little film of Epidote grow right past him; stopping his own summit for it; and he never himself grows any more.
"The Ethics of the Dust"
John Ruskin