Formation
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.
  
Carbonatites are intrusive or extrusive igneous rocks which are defined by mineralogic composition consisting of greater than 50 percent carbonate minerals and are formed due to low degrees of partial melting of rocks.
  
Composition
  
  
Mineral Content
Biotite, Olivine, Plagioclase, Pyrrhotite
  
Ancylite, Apatite, Barite, Fluorite, Magnetite, Natrolite, Sodalite
  
Compound Content
Al, CaO, Carbon Dioxide, Mg, MgO
  
CaO, Carbon Dioxide, Sodium Oxide
  
Transformation
  
  
Metamorphism
Yes
  
Yes
  
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Impact Metamorphism, Regional Metamorphism
  
Burial Metamorphism, Contact Metamorphism
  
Weathering
Yes
  
Yes
  
Types of Weathering
Biological Weathering
  
Biological Weathering, Chemical Weathering, Mechanical Weathering
  
Erosion
Yes
  
Yes
  
Types of Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion, Sea Erosion, Water Erosion, Wind Erosion
  
Chemical Erosion, Wind Erosion
  
Picrite and Carbonatite Formation
Formation of rocks is a long process and hence, Picrite and Carbonatite formation sounds very interesting. According to the formation, all rocks are divided into :Igneous Rocks, Fossil Rocks and Metamorphic Rocks. Igneous rocks form by crystallization of magma or lava. The magma is made up of various components of pre-existing rocks which have been subjected to melting either at subduction zones or within the Earth's mantle. Igneous rocks are generally seen at mid ocean ridges or in intra-plate hotspots. Sedimentary rocks are formed when sediments accumulate gradually. As the sediments are buried they get compacted as more and more material is deposited on top. Eventually the sediments become so dense that they form a rock. Metamorphic rocks are rocks which once existed as igneous or sedimentary rocks but have been subjected to varying degrees of pressure and heat within the Earth's crust. Get to know all about formation of Picrite and Carbonatite, composition of Picrite and Carbonatite and their transformation.