Hornfels

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hornfels

[′hȯr‚felz]
(petrology)
A common name for a class of metamorphic rocks produced by contact metamorphism and characterized by equidimensional grains without preferred orientation.

Hornfels

 

a dense, fine-grained rock produced by the action of an instrusive body on the enclosing rocks. Hornfels differs in composition from the rocks that have been metamorphosed. Clay rocks become hornfels containing cordierite, andalusite, sillimanite, garnet, biotite, and feldspars. Basalts, basalt tuffs, and graywackes become hornfels with pyroxenes, basic plagioclase, and hornblende. Marls become hornfels with wollastonite, olivine, spinel, and carbonates. As the quantity of carbonates increases, hornfels become contact marbles.

References in periodicals archive ?
25 km east of the Prince of Wales target, a significant zone of sulphide bearing biotite hornfels within Knob Hill Formation sediments was intersected adjacent to an intensely propylitic altered diorite in drillhole 10CM06, yielding 0.
8) Total 509 (100) 577 (100) Table 2: The number of core types per raw material for both assemblages Assemblage Core type Basalt Chert Hornfels Quartz Booroola 3 Bifacial 6 Bipolar 1 Unifacial 1 11 Mount Bifacial 1 1 Alexina 1 Bipolar 2 Microblade Multifacial 2 Unifacial 1 1 1 Assemblage Core type Silcrete Total Booroola 3 Bifacial 1 7 Bipolar 1 Unifacial 5 17 Mount Bifacial 1 3 Alexina 1 Bipolar 2 Microblade 2 2 Multifacial 1 3 Unifacial 3 6 Table 3: The number and (percentage) of artefact types per raw material for both assemblages Assemblage Artefact type Quartz Silcrete Booroola 3 Broken flake 278 (66.
Company geologists were able to access the contact zone between the MacAdam Intrusive and the Hornfels at the eastern side of the newly uncovered glacial valley.
Hornfels is not a common rock-type within England and Wales but exposures are known surrounding the granite outcrops of Devon and Cornwall where Devonian-Lower Carboniferous sediments have been baked by the Cornubian batholith.
Grey hornfels with strong silica alteration and diss.
4km in area remain open to the northwest and southeast, coincident with outcropping coarse grained porphyritic intrusive rocks and overlying zones of mineralized hornfels.
The drill rig has now moved to the Buccaneer Porphyry Prospect and TB Hornfels Prospect where ABM Resources is completing an initial 10 holes before returning to the Old Pirate and the Old Pirate South Prospects.
Biotite hornfels is developed locally in the contact zone near Lake Utopia, and equigranular to porphyritic microgranite is common along the southern contact of the granite, consistent with the intrusive relationship (McLeod 1990).
The tools are made predominantly of hornfels and dolerite, but there are a few quartz pieces.
5 m zone of elevated copper values within hornfels altered intermediate volcanic rocks.
0x20 These structures are being carefully sampled to determine if one of them was the pathway along which mineralizing fluids escaped from beneath the hornfels into the upper, manto-hosting limestone units.
Hornfels and skarn developed mainly in Cambrian units indicate the presence of unexposed plutons in the Blue Mountain area (location "m", Fig.