The Irish Hill district is in northwestern Amador County about five miles north of Ione. It includes the Muletown and the Forest Home areas.
Several extensive patches of Eocene quartz-rich channel gravels and younger gravels exist. They were first mined by ground sluicing and hydraulicking and later by dragline dredging. Bedrock consists of slate, phyllite, greenstone, and amphibolite. There are also several copper mines here.
Piper, A. M., Gale, H.S., Thomas, H.E., and Robinson, T. W., 1939, Geology and ground-water hydrology of the Mokelumne area: U.S. Geol. Survey Water Supply Paper 780, plate 1.
Turner, H. W., 1894, Jackson folio: U.S. Geol. Survey Geol. Atlas of the U. S., folio 11. 6 pp.