Komatiite

Classification：Igneous Rock

A ultrabasic igneous rock formed by partial melting, mainly composed of olivine and pyroxene, has a special spinifex structure. The fact that comalti rock is no longer formed is presumably due to the cooling of the mantle, which can not meet the partial melting at high temperature.

Komatiite is an ultrabasic eruption rock. For the first time in 1969 was found in South Africa Burton Ba mountain komati basin (Komati), named. Originally only spinifex texture ultramafic lavas with pillow lavas at the top of the Archean greenstone.

Komatiite is a kind of ultramafic lavas crystallized from high temperature magma containing MgO 18%~32%. The composition is equivalent to the deep peridotite. A occipital structure is often formed, with a condensing flow cap and usually a well developed hyena structure: in large amounts of vitreous matrix, olivine and pyroxene crystals are intergranular or blade shaped, often interbedded with lamellar basalt, and the more magnesium rich species are often called peridotite Komatiite. It can be determined by chemical composition in the TAS diagram. It originated in South Africa Telansiwaba Burton komati.
The rocks are mainly composed of olivine, pyroxene speckles (or skeletons) and a small amount of chrome spinel and glass matrix, with occipital structure, detrital structure, and typical hyenas (fishbone or pinnate) structures characterized by long serrated speckles of olivine and a product of quenching crystallization. Typical Komatiite in chemical composition is characterized by MgO>18% (anhydrous), CaO:Al2O3>1, high Ni, Cr, Fe/Mg and low alkali.
In the early stage of petrology, it was considered that ultrabasic rocks are non ejecting facies rocks. The discovery of Komatiite is of great significance to confirm the magma genesis of ultrabasic rocks. It is the product of partial melting of mantle height, and is the representative of the early mg rich primary magma in the earth. Now the word "Komatiite" has been expanded, and the generalized Komatiite also includes the basalt with genetic connection and some characteristics of Komatiite. So some people think that in the mineral composition and structure should also include rapid growth, with the rod-shaped skeleton crystal structure of pyroxene. In chemical composition, MgO>12% (or >9%) and CaO: Al2O3>0.8 of basaltic Komatiite are proposed. Some people classified the generalized Komatiite into olive Komatiite (typical Komatiite), basaltic Komatiite and K Ma Ti basalt, and used cautiously for the latter two. Komatiite is often found in Archean greenstone in South Africa, Western Australia, Finland, the United States and Canada.
Komatiite is often found in Archean greenstone in South Africa, Western Australia, Finland, the United States and Canada. Komatiite related minerals include gold, copper, antimony and nickel. Nickel deposits are very abundant, sometimes there are mineral deposits such as chrysotile, magnesite and talc.