Definition of "hornfels" []

• A fine-grained metamorphic rock composed of quartz, feldspar, mica, and other minerals, formed by the action of intrusive rock upon sedimentary rock, especially shale. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "They went single file, stopping once to clear a rockfall, pitching splintered chunks of shale and hornfels into the groan - ing trench to their right."
• "The preliminary, widely spaced five hole drill program encountered anomalous gold, arsenic and base-metals in intervals tens-of-metres thick with silicification, pyritic sulphides, within variable skarn and hornfels alteration."
• "-- TB High Grade Zone - 500 metre of anomalous hornfels zone with drill results including:"