KREEP

Lunar igneous rockOne of the three basic types of rock that also include sedimentary and metamorphic. Igneous rocks are formed by the solidification of magma and comprised predominately of silicate minerals. Based on bulk chemical analysis, igneous rocks can be grouped into four major groups based on their SiO2 content: 1. Felsic: rich in potassium (K), rare-earth elements (REEOften abbreviated as “REE”, these 16 elements include (preceded by their atomic numbers): 21 scandium (Sc), 39 Yttrium (Y) and the 14 elements that comprise the lanthanides excluding 61 Promethium, an extremely rare and radioactive element. These elements show closely related geochemical behaviors associated with their filled 4f atomic orbital.), phosphorus (P), thorium, and other incompatible elements. These elements are not incorporated into common rock-forming minerals during magmaMolten silicate (rock) beneath the surface of a planetary body or moon. When it reaches the surface, magma is called lava. crystallizationPhysical or chemical process or action that results in the formation of regularly-shaped, -sized, and -patterned solid forms known as crystals., and become enriched in the residual magma and the rocks that ultimately crystallize from it.