Volcanic rock While still dominated by silicates, more primitive volcanic rocks have mineral assemblages with less silica, such as olivine and the pyroxenes. Bowen's reaction series correctly predicts the order of formation of the most common minerals in volcanic rocks. Occasionally, a magma may pick up crystals that crystallized from another magma; these crystals are called xenocrysts. Diamonds found in kimberlites are rare but well-known xenocrysts; the kimberlites do not create the diamonds, but pick them up and transport them to the surface of the Earth. Volcanic rocks are named according to both their chemical composition and texture. Basalt is a very
Kimberlite the extreme magma composition that it reflects in terms of low silica content and high levels of incompatible trace-element enrichment make an understanding of kimberlite petrogenesis important. In this regard, the study of kimberlite has the potential to provide information about the composition of the deep mantle and melting processes occurring at or near the interface between the cratonic continental lithosphere and the underlying convecting asthenospheric mantle. Many kimberlite structures are emplaced as carrot-shaped, vertical intrusions termed "pipes". This classic carrot shape is formed due to a complex intrusive process of kimberlitic magma, which inherits a large proportion of CO