Jackson, in his "Report on the Geology of Maine," says: "hornstone, which will answer for flints, occurs in various parts of the State.
"Canoeing in the wilderness"
Henry David Thoreau
In the bed of the river, whose waters are beautifully clear, are hornstone rocks, dipping north-east, and striking north-west.
"Himalayan Journals V2."
J. D. Hooker
Another of the dikes of the north-east of Ireland has converted a mass of red sandstone into hornstone.
"The Student's Elements of Geology"
Sir Charles Lyell