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
Mylonite is a metamorphic rock formed by ductile deformation during intense shearing encountered during folding and faulting, a process termed cataclastic or dynamic metamorphism
Origin
New Zealand
New Zealand
Discoverer
Unknown
Unknown
Etymology
From German which means hornstone
From Greek mulōn mill + -ite
Class
Metamorphic Rocks
Metamorphic Rocks
Sub-Class
Durable Rock, Soft Rock
Durable Rock, Medium Hardness Rock
Group
Not Applicable
Not Applicable
Other Categories
Fine Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Granular, Platy
Foliated
Color
Brown, Dark Greenish - Grey, Green, Reddish Brown
Black to Grey
Durability
Durable
Durable
Appearance
Dull
Dull, Banded and Foilated
Interior Uses
Decorative Aggregates, Flooring, Homes, Interior Decoration
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
Other Architectural Uses
Curbing
Curbing
Construction Industry
for Road Aggregate, Roadstone
for Road Aggregate, Landscaping, Roadstone
Medical Industry
Not Yet Used
Not Yet Used
Antiquity Uses
Artifacts, Monuments
Artifacts, Monuments
Commercial Uses
Cemetery Markers, Commemorative Tablets, Creating Artwork
Creating Artwork, Gemstone, Jewelry
Types
Biotite hornfels
Blastomylonites, Ultramylonites and Phyllonites
Features
Smooth to touch
Surfaces are often shiny
Archaeological Significance
Famous Monuments
Data Not Available
Data Not Available
Sculpture
Not Yet Used
Used
Famous Sculptures
Not Applicable
Data Not Available
Figurines
Not Yet Used
Used
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.
Mylonites are ductilely deformed rocks formed by the accumulation of large shear strain, in ductile fault zones.
Mineral Content
Andalusite
Porphyroblasts
Compound Content
Fe, Mg
Aluminium Oxide, Calcium Sulfate, Chromium(III) Oxide, Iron(III) Oxide, Magnesium Carbonate, Silicon Dioxide
Types of Metamorphism
Not Applicable
Not Applicable
Types of Weathering
Biological Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Types of Erosion
Chemical Erosion, Glacier Erosion, Sea Erosion, Water Erosion, Wind Erosion
Chemical Erosion, Sea Erosion, Wind Erosion
Grain Size
Fine Grained
Fine Grained
Fracture
Conchoidal
Conchoidal
Porosity
Highly Porous
Highly Porous
Cleavage
Perfect
Conchoidal
Toughness
Not Yet Found
Not Available
Specific Gravity
3.4-3.9
2.97-3.05
Transparency
Opaque
Opaque
Density
0.25-0.30 g/cm3
2.6-4.8 g/cm3
Resistance
Heat Resistant, Impact Resistant, Pressure Resistant
Heat Resistant, Impact Resistant, Pressure Resistant
Deposits in Eastern Continents
Asia
Bangladesh, Bhutan, China, India, North Korea, Qatar, Russia, Saudi Arabia, South Korea, Thailand
China, India, Indonesia, Saudi Arabia, South Korea
Africa
Cameroon, East Africa, Tanzania, Western Africa
Eritrea, Ethiopia, Ghana, South Africa, Western Africa
Europe
United Kingdom
England, Finland, France, Germany, Great Britain, Greece, United Kingdom
Others
Not Yet Found
Not Yet Found
Deposits in Western Continents
North America
Canada, USA
USA
South America
Bolivia, Brazil, Colombia, Ecuador
Not Yet Found
Deposits in Oceania Continent
Australia
New South Wales, New Zealand, Queensland, Western Australia
Central Australia, Western Australia