Sanukitoid

[1][2][3][4] They are called "sanukitoid" because of their similarity in bulk chemical composition to high-magnesium andesite from the Setouchi Peninsula of Japan, known as "sanukites" or "setouchites".

[5] Sanukite rocks are an andesite characterized by orthopyroxene as the mafic mineral, andesine as the plagioclase, and a glassy groundmass.

Sanukitoids are similar in trace element compositions to "adakites"[6] but with higher Mg and lower silica.

Both suites are thought to form by melting of a mafic igneous rock protolith that has been metamorphosed to garnet-pyroxene (eclogite) or garnet-amphibole assemblages.

Sanukitoids and adakites are distinct from another variety of high-Mg andesite called boninite; boninites have major element concentrations similar to sanukitoids, but they are extremely depleted in incompatible trace elements (e.g., LREE) despite their relatively high silica contents.