Hornfels

Type	Metamorphic Rock
Texture	Non-foliated; Very fine-grained
Composition	variable
Index Minerals
Color	mottled brownish green
Miscellaneous	Very hard
Metamorphic Type	Contact
Metamorphic Grade	Variable
Parent Rock	Shale or Mudstone
Metamorphic Environment	Contact metamorphism; immediately adjacent to igneous intrusion at shallow depths