The story
From mine + field. Compare Saterland Frisian Mienenfäield (“minefield”), West Frisian mynfjild (“minefield”), Dutch mijnenveld (“minefield”), German Low German Minenfeld (“minefield”), German Minenfeld (“minefield”), Danish minefelt (“minefield”), Swedish minfält (“minefield”).
Etymology from Wiktionary, CC BY-SA 4.0.