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
Picrite is a variety of high-magnesium olivine basalt that is very rich in the mineral olivine
Origin
New Zealand
Hawaii Islands
Discoverer
Unknown
Unknown
Etymology
From German which means hornstone
From Greek pikros bitter + -ite, 19th century
Class
Metamorphic Rocks
Igneous Rocks
Sub-Class
Durable Rock, Soft Rock
Durable Rock, Hard Rock
Other Categories
Fine Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Granular, Platy
Earthy, Rough
Color
Brown, Dark Greenish - Grey, Green, Reddish Brown
Black, Brown, Green, Grey, Pink, White, Yellow
Durability
Durable
Durable
Appearance
Dull
Rough and Shiny
Interior Uses
Decorative Aggregates, Flooring, Homes, Interior Decoration
Countertops, Decorative Aggregates, Homes, Interior Decoration
Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration, Office Buildings, Paving Stone
As Building Stone, As Facing Stone, Garden Decoration, Paving Stone
Other Architectural Uses
Curbing
Curbing
Construction Industry
for Road Aggregate, Roadstone
As a Sintering Agent in Steel Industry to process Iron Ore, Cement Manufacture, for Road Aggregate, Manufacture of Magnesium and Dolomite Refractories, Roadstone, Used for flooring, stair treads, borders and window sills.
Antiquity Uses
Artifacts, Monuments
Artifacts, Monuments, Sculpture
Commercial Uses
Cemetery Markers, Commemorative Tablets, Creating Artwork
As a Feed Additive for Livestock, As armour rock for sea walls, Metallurgical Flux, Pottery, Source of Magnesia (MgO)
Types
Biotite hornfels
Oceanite
Features
Smooth to touch
Host Rock for Lead
Archaeological Significance
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.
Picrite is a fine-grained, hard rock which is a type of metasomatite, essentially altered basalt. It forms with or without crystallization, either below the surface as intrusive rocks or on the surface as extrusive rocks.
Mineral Content
Andalusite
Biotite, Olivine, Plagioclase, Pyrrhotite
Compound Content
Fe, Mg
Al, CaO, Carbon Dioxide, Mg, MgO
Types of Metamorphism
-
Burial Metamorphism, Cataclastic Metamorphism, Impact Metamorphism, Regional Metamorphism
Types of Weathering
Biological Weathering
Biological Weathering
Types of Erosion
Chemical Erosion, Glacier Erosion, Sea Erosion, Water Erosion, Wind Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion, Sea Erosion, Water Erosion, Wind Erosion
Grain Size
Fine Grained
Fine Grained
Fracture
Conchoidal
Uneven
Streak
-
White, Greenish White or Grey
Porosity
Highly Porous
Less Porous
Luster
Shiny
Subvitreous to Dull
Specific Gravity
3.4-3.9
2.75-2.92
Transparency
Opaque
Opaque
Density
0.25-0.30 g/cm3
1.5-2.5 g/cm3
Resistance
Heat Resistant, Impact Resistant, Pressure Resistant
Heat Resistant
Deposits in Eastern Continents
Asia
Bangladesh, Bhutan, China, India, North Korea, Qatar, Russia, Saudi Arabia, South Korea, Thailand
India, Russia
Africa
Cameroon, East Africa, Tanzania, Western Africa
South Africa
Europe
United Kingdom
Iceland
Deposits in Western Continents
North America
Canada, USA
Canada, USA
South America
Bolivia, Brazil, Colombia, Ecuador
Brazil
Deposits in Oceania Continent
Australia
New South Wales, New Zealand, Queensland, Western Australia
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Hornfels vs Picrite Characteristics
Though some rocks look identical, they have certain characteristics which distinguish them from others. Characteristics of rocks include texture, appearance, color, fracture, streak, hardness etc. Hornfels vs Picrite characteristics assist us to distinguish and recognize rocks. Also you can check about Properties of Hornfels and Properties of Picrite. Learn more about Hornfels vs Picrite in the next section. The interior uses of Hornfels include Decorative aggregates, Flooring, Homes and Interior decoration whereas the interior uses of Picrite include Countertops, Decorative aggregates, Homes and Interior decoration. Due to some exceptional properties of Hornfels and Picrite, they have various applications in construction industry. The uses of Hornfels in construction industry include For road aggregate, Roadstone and that of Picrite include As a sintering agent in steel industry to process iron ore, Cement manufacture, For road aggregate, Manufacture of magnesium and dolomite refractories, Roadstone, Used for flooring, stair treads, borders and window sills..
More about Hornfels and Picrite
Here you can know more about Hornfels and Picrite. The life cycle of a rock consists of formation of rock, composition of rock and transformation of rock. The composition of Hornfels and Picrite consists of mineral content and compound content. The mineral content of Hornfels includes Andalusite and mineral content of Picrite includes Biotite, Olivine, Plagioclase, Pyrrhotite. You can also check out the list of all Metamorphic Rocks. When we have to compare Hornfels vs Picrite, the texture, color and appearance plays an important role in determining the type of rock. Hornfels is available in brown, dark greenish - grey, green, reddish brown colors whereas, Picrite is available in black, brown, green, grey, pink, white, yellow colors. Appearance of Hornfels is Dull and that of Picrite is Rough and Shiny. Properties of rock is another aspect for Hornfels vs Picrite. The hardness of Hornfels is 2-3 and that of Picrite is 6.8. The types of Hornfels are Biotite hornfels whereas types of Picrite are Oceanite. Streak of rock is the color of powder produced when it is dragged across an unweathered surface. The streak of Hornfels is while that of Picrite is white, greenish white or grey. The specific heat capacity of Hornfels is 0.84 kJ/Kg K and that of Picrite is 0.88 kJ/Kg K. Depending on the properties like hardness, toughness, specific heat capacity, porosity etc., rocks are resistant to heat, wear, impact, etc.Hornfels is heat resistant, impact resistant, pressure resistant whereas Picrite is heat resistant.