Antonio Coronel was a Mexican Californio who like many other Spanish speakers was ejected by Anglos from his claim in the Gold Rush, about April, 1849. Quoting from the published translation of his memoir, Tales of Mexican California:
I was elected captain of the group in order to lay down some ground rules to ensure our safety. ... No one was to go to Sutter's Mill. ... In Ramon Carrillo's party there was an Irishman, long established in the country -- a good fellow, but fond of his whiskey. ... Féliz and the Irishman had gotten over two pounds of gold between them in the first week. ... But Saturday night the Irishman disappeared with his share of gold to Sutter's Mill. He got drunk and revealed all our business, plans, rules, and so forth. ... Every day more and more armed men came by to make inquiries, as before, but they were so familiar with our affairs that by Saturday the gunmen had set up camp beside us. ... At about 10am, a hundred of those soulless bandits invaded our claims, while we were down in them.
Who was the Irishman?
One prominent Irish immigrant in Northern California was Timothy Murphy, previously known to buy liquor at Fort Ross; nonetheless, as a mission administrator and rancho grantee, he seems unlikely to have mined in someone else's party.