from The American Heritage® Dictionary of the English Language, 4th Edition
- n. 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.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. Any of a series of contact metamorphic rocks that have been baked and indurated by the heat of intrusive igneous masses and rendered massive, hard, splintery, and in some cases exceedingly tough and durable.
from The Century Dictionary and Cyclopedia
- n. In petrography, a dense, aphanitic rock composed of feldspar, quartz, and other minerals, usually a product of the contact-metamorphism of an intrusive rock upon shale or other sedimentary rock. Sometimes called hornstone.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. a fine-grained metamorphic rock formed by the action of heat on clay rocks
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:
(VTEM) surveys flown in 2008 showed that outcropping granitic plugs are marked by magnetic lows while hornfels altered zones underlie magnetic highs.
The iron-rich skarn rocks, as well as other skarn types including epidote-silica skarns and sulphide-rich skarns, and hornfels rocks have been mapped as covering an area approximately 2,000 metres east-west by >
- Strong quartz stockwork with molybdenite in biotite hornfels has been observed adjacent to the Ethel zone (Drill Hole MX07-01).
- A fragment (or xenolith) of well mineralized intrusive within barren granodiorite was observed in drill hole MX07-03; - Disseminated molybdenite has recently been observed in intrusive rocks at the 805 mine level, currently below the Z zone described previously; and, - Strong quartz stockwork with molybdenite in biotite hornfels has been observed adjacent to the Ethel zone (Drill Hole MX07-01).
Three of the seven holes penetrate into a high temperature hornfels altered package of sediments below a near-horizontal fault.
When plate tectonic activity formed the Rocky Mountains, the hornfels lifted up along with the shale that surrounded it.
Guano Prospect: The Guano occurrence consists of hornfels and diopside-calcite-phlogopite skarn located at the metamorphic aureole of a syenite intrusive of Mississippian age.