Miniera vs. mina
The English word "mine" translates into Italian differently depending on its context. Although they are related in origin, miniera and mina have completely different meanings in modern Italian and cannot be used interchangeably.
Miniera
B1The word miniera refers specifically to a mining site, which is an underground or open-pit location where minerals, metals, or stones like coal, gold, and diamonds are extracted from the earth.
Mio nonno ha lavorato in una miniera di carbone per quarant'anni.
(My grandfather worked in a coal mine for forty years.)
I soccorritori stanno cercando di raggiungere gli operai bloccati nella miniera d'oro.
(Rescuers are trying to reach the workers trapped in the gold mine.)
Hanno trasformato la vecchia miniera di sale in una bellissima attrazione turistica.
(They turned the old salt mine into a beautiful tourist attraction.)
L'economia di quella piccola nazione si basa interamente sulla miniera di diamanti.
(The economy of that small nation relies entirely on the diamond mine.)
I lavori di scavo nella nuova miniera di ferro inizieranno il mese prossimo.
(The excavation work in the new iron mine will start next month.)
Mina
B2The word mina translates the English word "mine" only when referring to an explosive device, such as a landmine or a naval mine. It is never used to describe a place of extraction for coal or gold, though it is also the standard Italian word for the graphite lead inside a pencil.
I soldati hanno bonificato il campo per rimuovere ogni mina inesplosa.
(The soldiers cleared the field to remove every unexploded mine.)
La vecchia nave mercantile è affondata dopo aver urtato una mina navale.
(The old merchant ship sank after hitting a naval mine.)
Devo temperare la mia matita perché la mina si è appena spezzata.
(I have to sharpen my pencil because the lead just broke.)
Il cartello rosso avverte del pericolo di calpestare una mina antiuomo.
(The red sign warns of the danger of stepping on a landmine.)
Gli ingegneri hanno posizionato una mina per distruggere le rocce durante i lavori stradali.
(The engineers placed an explosive mine to destroy the rocks during the roadworks.)
Summary
In short, use miniera when talking about a facility or geographical location for extracting valuable resources like coal, salt, or gold. Use mina when talking about an explosive weapon or the graphite core of a pencil.