noun which may take the genitive case particle 'no', noun
mafic
Geological term describing igneous rocks or minerals rich in magnesium and iron, typically dark-colored. Used attributively with の.
See also: 珪長質
玄武岩は苦鉄質の火山岩である。
Basalt is a mafic volcanic rock.
苦鉄質鉱物にはカンラン石や輝石が含まれる。
Mafic minerals include olivine and pyroxene.
Compound of 苦 (bitter, here representing magnesium) + 鉄 (iron) + 質 (quality, nature), calqued from English 'mafic' (magnesium + ferric).