hornfels

American  

[hawrn-felz] / ˈhɔrn fɛlz /

noun

1. a dark, fine-grained metamorphic rock, the result of recrystallization of siliceous or argillaceous sediments by contact metamorphism.

---

hornfels British  

/ ˈhɔːnfɛlz /

noun

1. Also called: hornstone.  a hard compact fine-grained metamorphic rock formed by the action of heat from a magmatic intrusion on neighbouring sedimentary rocks

---

hornfels Scientific  

/ hôrn′fĕlz′ /

1. A fine-grained metamorphic rock having a uniform grain size and formed by contact metamorphism.

---

Etymology

Origin of hornfels

1850–55; < German, equivalent to Horn horn + Fels rock, cliff

Example Sentences

Crystals in hornfels grow smaller with metamorphism and become so small that specialized study is required to identify them.

From Textbooks • Jan. 1, 2017

The protolith of hornfels can be even harder to distinguish, which can be anything from mudstone to basalt.

From Textbooks • Jan. 1, 2017

Metamorphic rocks formed in environments without strong directed pressure include hornfels, marble, and quartzite.

From Textbooks • Jan. 1, 2015

In some cases, hornfels has visible crystals of minerals like biotite or andalusite.

From Textbooks • Jan. 1, 2015

They are excessively variable in their mineralogical composition, and very often alternate in thin seams with biotite hornfels and indurated quartzites.

From Encyclopaedia Britannica, 11th Edition, Volume 13, Slice 6 "Home, Daniel" to "Hortensius, Quintus" by Various