Found along the Bahia river of Brazil are the heavily river-worn agates with weathered colors. It's typical to find horizontally banded agates and apparently, many agates had been partially opalized that it's tricky to cut them without breaking too much of the edges. The agates can be identified by the messy but interesting colors within some agates as a result of weathering. The colors are mainly tan, white, yellow, pink and red. Some agates are so river-worn that  many agates will have incomplete patterns within.