'hornblende-deficient' is a compound of 'hornblende' and 'deficient'. 'hornblende' originates from German, specifically the word 'Hornblende', where 'Horn' originally meant 'horn' and 'Blende' was used for minerals that 'deceive' (a historical mineral term). 'deficient' originates from Latin, specifically the participle of 'deficere', where 'de-' meant 'away' and 'ficere' (from 'facere' via alteration) meant 'to make/do' or 'to fail' in the compound sense.

'hornblende' was adopted into English in the 19th century as a mineral name from German 'Hornblende'. 'deficient' passed into English via Old French from Latin 'deficere' through Middle English, becoming the modern adjective 'deficient'. The compound form 'hornblende-deficient' is a modern descriptive formation used in geological contexts.

Individually the elements kept their senses (a mineral named for horn-like appearance and the idea of lacking). Together the compound's meaning crystallized into the technical notion of 'lacking hornblende' in a rock; the combined meaning is specialized rather than metaphorical.