1. Map showing exposures of limonitic rocks and hydrothermally altered rocks in the Dillon 1⁰?x 2⁰?quadrangle, Idaho and Montana Yale Public content 1989. 2002-06-01T04:00:00Z. 2002-06-01T04:00:00Z. Geological Survey (U.S.). The Survey ; For sale by Map Distribution. English. Public. Idaho and Montana.