'anorthosite-rich' is a recent English compound formed from 'anorthosite' + the adjectival combining element '-rich' (meaning 'abounding in'). 'Anorthosite' itself comes from New Latin 'anorthosite', ultimately built from Greek elements and the mineral suffix '-ite'.

'anorthosite' was adopted in scientific usage from New Latin/Greek-based mineral naming in the 19th century; later, English productivity created the compound 'anorthosite-rich' by adding the native element '-rich' to indicate abundance.

The compound has a literal compositional meaning: initially and still, it denotes 'abundant in anorthosite' rather than a figurative sense.