'calcium' originates from New Latin and Latin, specifically the Latin word 'calx', where 'calx' meant 'lime'. 'rich' originates from Old English, specifically the word 'rīce' (later 'rice'), where 'rīce' meant 'powerful' or 'wealthy'.

'calcium' changed from the Latin 'calx' into New Latin 'calcium' (used in chemistry for the element) and then entered modern English as 'calcium'. 'rich' changed from Old English 'rīce' (meaning powerful/wealthy) through Middle English into the modern English word 'rich'.

Initially, 'calx' referred to 'lime' (the substance); over time 'calcium' came to name the chemical element and, by extension, compounds or materials containing it. 'Rich' initially meant 'powerful/wealthy' and evolved to mean 'abundant' or 'having a lot of (something)', as in 'rich in X'.