1. a fine-grained metamorphic rock formed by contact metamorphism when existing rock is heated by nearby magma
Usage: geology

Examples

• The geologist identified the dark, hard rock as hornfels.
• Hornfels forms when shale or other rocks are baked by hot magma.
• The mountain contained layers of hornfels created by ancient volcanic activity.
• Students examined samples of hornfels in their geology lab.
• The quarry exposed a large deposit of hornfels rock.
• Hornfels is typically much harder than the original rock it formed from.