Definition
Arkose is a sedimentary rock, specifically a type of sandstone containing at least 25% feldspar
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
Origin
France
New Zealand
Discoverer
Alexandre Brongniart
Unknown
Etymology
From Auvergne region of France used by a French geologist Alexandre Brongniart in 1826 who applied this term to some feldspathic sandstones
From German which means hornstone
Class
Sedimentary Rocks
Metamorphic Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Soft Rock
Group
Not Applicable
Not Applicable
Other Categories
Coarse Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Clastic
Granular, Platy
Color
Reddish Brown
Brown, Dark Greenish - Grey, Green, Reddish Brown
Durability
Durable
Durable
Appearance
Rough and Dull
Dull
Interior Uses
Decorative Aggregates, Homes, Interior Decoration
Decorative Aggregates, Flooring, Homes, Interior Decoration
Exterior Uses
Paving Stone, Office Buildings
As Building Stone, As Facing Stone, Garden Decoration, Office Buildings, Paving Stone
Other Architectural Uses
Whetstones
Curbing
Construction Industry
Cement Manufacture, Construction Aggregate, for Road Aggregate, Production of Glass and Ceramics, Raw material for the manufacture of mortar
for Road Aggregate, Roadstone
Medical Industry
Not Yet Used
Not Yet Used
Antiquity Uses
Artifacts, Sculpture, Small Figurines
Artifacts, Monuments
Commercial Uses
In aquifers, Soil Conditioner, Source of Magnesia (MgO), Tombstones
Cemetery Markers, Commemorative Tablets, Creating Artwork
Types
Not Available
Biotite hornfels
Features
Available in Lots of Colors and Patterns, Generally rough to touch, Is one of the oldest rock
Smooth to touch
Archaeological Significance
Monuments
Not Yet Used
Used
Famous Monuments
Not Applicable
Data Not Available
Sculpture
Used
Not Yet Used
Famous Sculptures
Data Not Available
Not Applicable
Pictographs
Not Used
Used
Petroglyphs
Not Used
Used
Figurines
Used
Not Yet Used
Formation
Arkose rock forms from the weathering of feldspar-rich igneous or metamorphic rock, most commonly granitic rocks, which are primarily composed of quartz and feldspar.
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.
Mineral Content
Calcite, Clay, Clay Minerals, Feldspar, Micas, Quartz
Andalusite
Compound Content
Aluminium Oxide, CaO, Iron(III) Oxide, Potassium Oxide, MgO, Sodium Oxide, Silicon Dioxide
Fe, Mg
Types of Metamorphism
Not Applicable
Not Applicable
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Biological Weathering
Types of Erosion
Coastal Erosion, Glacier Erosion, Water Erosion, Wind Erosion
Chemical Erosion, Glacier Erosion, Sea Erosion, Water Erosion, Wind Erosion
Grain Size
Coarse Grained
Fine Grained
Fracture
Conchoidal
Conchoidal
Porosity
Highly Porous
Highly Porous
Compressive Strength
Not Available
Cleavage
Not Available
Perfect
Toughness
Not Available
Not Yet Found
Specific Gravity
0
3.4-3.9
Transparency
Opaque
Opaque
Density
Not Available
0.25-0.30 g/cm3
Specific Heat Capacity
Not Available
Resistance
Heat Resistant, Impact Resistant, Pressure Resistant
Heat Resistant, Impact Resistant, Pressure Resistant
Deposits in Eastern Continents
Asia
China, India, Kazakhstan, Mongolia, Russia, Uzbekistan
Bangladesh, Bhutan, China, India, North Korea, Qatar, Russia, Saudi Arabia, South Korea, Thailand
Africa
Namibia, Nigeria, South Africa
Cameroon, East Africa, Tanzania, Western Africa
Europe
Austria, Denmark, Germany, Great Britain, Netherlands, Norway, Poland, Sweden, Switzerland, United Kingdom
United Kingdom
Others
Greenland
Not Yet Found
Deposits in Western Continents
North America
Canada, USA
Canada, USA
South America
Brazil
Bolivia, Brazil, Colombia, Ecuador
Deposits in Oceania Continent
Australia
New South Wales, New Zealand
New South Wales, New Zealand, Queensland, Western Australia