Definition
Definition
Hornfels is a metamorphic rock formed by the contact between mudstone or other clay rich rock, and a hot igneous body, and represents a heat altered equivalent of the original rock
Gossan is intensely oxidized, weathered or decomposed rock, usually the upper and exposed part of an ore deposit or mineral vein.
History
Origin
New Zealand
Indonesia
Discoverer
Unknown
Cornish Gossen
Etymology
From German which means hornstone
From Cornish gossen from gos, blood from Old Cornish guit
Class
Metamorphic Rocks
Metamorphic Rocks
Sub-Class
Durable Rock, Soft Rock
Durable Rock, Medium Hardness Rock
Family
Group
Not Applicable
Not Applicable
Other Categories
Fine Grained Rock, Opaque Rock
Fine Grained Rock, Medium Grained Rock, Opaque Rock
Texture
Texture
Granular, Platy
Rough, Sandy
Color
Brown, Dark Greenish - Grey, Green, Reddish Brown
Brown, Brown- Black, Gold, Green, Rust
Maintenance
Less
Less
Durability
Durable
Durable
Water Resistant
✔
✘
✔
✘
Scratch Resistant
✔
✘
✔
✘
Stain Resistant
✔
✘
✔
✘
Wind Resistant
✔
✘
✔
✘
Acid Resistant
✔
✘
✔
✘
Appearance
Dull
Dull and Banded
Uses
Architecture
Interior Uses
Decorative Aggregates, Flooring, Homes, Interior Decoration
Countertops, Decorative Aggregates, Interior Decoration
Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration, Office Buildings, Paving Stone
As Building Stone, As Facing Stone, Paving Stone, Garden Decoration, Office Buildings
Other Architectural Uses
Curbing
Curbing
Industry
Construction Industry
for Road Aggregate, Roadstone
As Dimension Stone, Cement Manufacture, Construction Aggregate, for Road Aggregate
Medical Industry
Not Available
Not Available
Antiquity Uses
Artifacts, Monuments
Artifacts
Other Uses
Commercial Uses
Cemetery Markers, Commemorative Tablets, Creating Artwork
Cemetery Markers, Commemorative Tablets, Gemstone
Types
Types
Biotite hornfels
Translocated gossan and Leakage gossan
Features
Smooth to touch
Clasts are smooth to touch, Easily splits into thin plates
Archaeological Significance
Monuments
Used
Not Yet Used
Famous Monuments
Not Available
Not Applicable
Sculpture
Not Yet Used
Not Yet Used
Famous Sculptures
Not Applicable
Not Applicable
Pictographs
Used
Used
Petroglyphs
Used
Used
Figurines
Not Yet Used
Not Yet Used
Fossils
Absent
Absent
Formation
Formation
Due to change in environmental conditions, rocks are heated and pressurized deep inside the Earth's surface. Hornfels is formed from the extreme heat caused by magma or by the intense collisions and friction of tectonic plates.
Earth movements can cause rocks to be either deeply buried or squeezed and hence the rocks are heated and put under great pressure.
Composition
Mineral Content
Andalusite
Apatite, Augite, Biotite, Bronzite, Calcite, Chert, Epidote, Feldspar, Hornblende, Micas, Plagioclase, Pyroxene, Quartz, Sulfides, Zircon
Compound Content
Fe, Mg
Aluminium Oxide, CaO, Fe, FeO, Silicon Dioxide, Sulphur
Transformation
Metamorphism
✔
✘
✔
✘
Types of Metamorphism
Not Applicable
Not Applicable
Weathering
✔
✘
✔
✘
Types of Weathering
Biological Weathering
Not Applicable
Erosion
✔
✘
✔
✘
Types of Erosion
Chemical Erosion, Glacier Erosion, Sea Erosion, Water Erosion, Wind Erosion
Chemical Erosion, Sea Erosion, Wind Erosion
Properties
Physical Properties
Hardness
2-34-5
1
7
👆🏻
Grain Size
Fine Grained
Fine to Medium Grained
Fracture
Conchoidal
Conchoidal
Streak
Unknown
White to Grey
Porosity
Highly Porous
Highly Porous
Luster
Shiny
Metallic
Compressive Strength
5.80 N/mm2NA
0.15
450
👆🏻
Cleavage
Perfect
Not Available
Toughness
Not Available
Not Available
Specific Gravity
3.4-3.92.0
0
8.4
👆🏻
Transparency
Opaque
Opaque
Density
0.25-0.30 g/cm3Not Available
0
1400
👆🏻
Thermal Properties
Specific Heat Capacity
0.84 kJ/Kg K0.24 kJ/Kg K
0.14
3.2
👆🏻
Resistance
Heat Resistant, Impact Resistant, Pressure Resistant
Heat Resistant, Impact Resistant, Pressure Resistant
Reserves
Deposits in Eastern Continents
Asia
Bangladesh, Bhutan, China, India, North Korea, Qatar, Russia, Saudi Arabia, South Korea, Thailand
China, India, Indonesia, Russia, Singapore, South Korea
Africa
Cameroon, East Africa, Tanzania, Western Africa
Cape Verde, Ethiopia, Ghana, South Africa, Western Africa
Europe
United Kingdom
Albania, France, Germany, Great Britain, United Kingdom
Others
Not Available
Not Available
Deposits in Western Continents
North America
Canada, USA
Canada, USA
South America
Bolivia, Brazil, Colombia, Ecuador
Brazil, Colombia, Ecuador
Deposits in Oceania Continent
Australia
New South Wales, New Zealand, Queensland, Western Australia
New South Wales, South Australia, Western Australia