mineral matter; mineral substance
Refers to inorganic, naturally occurring solid material with a definite chemical composition and crystalline structure; used in geology, chemistry, and materials science.
This rock contains a lot of mineral matter.
Specialized equipment is needed for the analysis of mineral substances.
無機物 means 'inorganic matter', a broader category that includes minerals but also non-mineral inorganic substances.
Compound of 鉱物 (mineral) + 質 (substance, quality). The exact historical derivation is uncertain, but the term is a straightforward technical compound.