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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All about Hornfels and Picrite Properties
Know all about Hornfels and Picrite properties here. All properties of rocks are important as they define the type of rock and its application. Hornfels belongs to Metamorphic Rocks while Picrite belongs to Igneous Rocks.Texture of Hornfels is Granular, Platy whereas that of Picrite is Earthy, Rough. Hornfels appears Dull and Picrite appears Rough and Shiny. The luster of Hornfels is shiny while that of Picrite is subvitreous to dull. 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. The commercial uses of Hornfels are cemetery markers, commemorative tablets, creating artwork and that of Picrite are as a feed additive for livestock, as armour rock for sea walls, metallurgical flux, pottery, source of magnesia (mgo).