'mixed-mineral' is a modern English compound formed from 'mixed' + 'mineral'. 'mixed' ultimately comes from Latin 'miscēre' (via Old French 'mescler' / Middle English) where the root meant 'to mix'; 'mineral' originates from Medieval Latin 'minerale' (from Latin 'minera' or related forms) where the root referred to a 'mine' or 'natural ore'.

'mixed-mineral' developed by combining the past-participle/adjective 'mixed' (from Latin 'miscēre' → Old French 'mescler' → Middle English) with 'mineral' (from Medieval Latin 'minerale'). The compound form in modern English arose to describe rocks or samples made of more than one mineral.

The individual parts originally referred to the action 'to mix' (miscēre) and to 'mine/ore' (minerale); over time the compound came to mean 'containing a mixture of different minerals' in geological and material contexts.