This is a great komatiite specimen from this exceedingly rare geological location. It has fantastic spinifex textured bladed olivine which is prominent and easily seen. (The "spinifex" texture is named after an Australian grass that grows in clumps with similar shapes). This komatiite also has some minor crust on one side.
Komatiite is a type of very rare igneous rock that is ultramafic, mantle-derived and from volcanic origin. Komatiites have low silicon, potassium and aluminum, and high to extremely high magnesium content. Komatiite was named for its specific type locality where it is found along the Komati River, in South Africa.
True komatiites are extremely rare to find on Earth. The age restriction (3.8 to 2.8 Ga) is thought to be due to cooling of the mantle, which scientists think may have been up to 500 degrees C hotter during the early to middle Archaean. The early Earth had much higher heat production, due to the residual heat from planetary accretion, as well as a greater abundance of radioactive elements.
Geographically, komatiites are restricted in distribution to the Archaean shield areas. Komatiites occur with other ultramafic and high magnesian mafic volcanic rocks in Archaean greenstone belts.
Pristine volcanic mineralogy of komatiites is composed of forstertic olivine, calcic and often chromian pyroxene, anorthite and chromite. Some of the highest magnesian komatiites with clear textural preservation are those of the Weltevreden Formation of the Barberton Greenstone Belt, in South Africa.
Komatiites are associated with nickel and gold deposits in Australia, Canada, South Africa and most recently in the Guinana shield of South America.
Size: 23mm H X 16mm W X 6mm D
Ships with Certificate of Authenticity, tag, tag stand, display case and information about the geological importance of the specimen. Legally collected. Stands and cube not included.
Komatiite is one of the more important and unusual geological specimens for a serious scientific rock collection. Extremely rare specimen.
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