hornstone

[ hawrn-stohn ]

/ ˈhɔrnˌstoʊn /

a variety of quartz resembling flint.

Origin of hornstone

1720–30; translation of German Hornstein

About ten miles north of this point, the upper calcareous, or surface rock, embraces nodules of hornstone.

Summary Narrative of an Exploratory Expedition to the Sources of the Mississippi River, in 1820 |Henry Rowe Schoolcraft
It was a piece of hornstone, which I told him his tribe had probably brought here centuries before to make arrowheads of.

The Maine Woods |Henry David Thoreau
The geological locality of hornstone is remarkable; for it occurs in both ancient and recent formations.

A Dictionary of Arts, Manufactures and Mines |Andrew Ure
The hornstone which occurs in secondary limestone is called chert by the English miners.

A Dictionary of Arts, Manufactures and Mines |Andrew Ure

Another of the dikes of the north-east of Ireland has converted a mass of red sandstone into hornstone.

A Manual of Elementary Geology |Charles Lyell.

hornstone

/ (ˈhɔːnˌstəʊn) /

another name for chert, hornfels

C17: translation of German Hornstein; so called from its appearance