The occurrence of unusual amounts of thallium in manganese ores from the Apache mine, Gila County, Arizona, was reported to the U. S. Geological Survey in 1943 by John Herman, of Smith-Emery Company, commercial analysts serving the Federal stockpile in Phoenix, Arizona. In June 1944, specimens from the Apache mine were included in a group of samples submitted to the laboratory by one of us (M.D.C.) to verify the presence of thallium and to determine the chemical nature of its occurrence. Spectrographic analysis by K. J. Murata of three samples from this mine showed that thallium was indeed present, in amounts estimated to be a few tenths of one per cent. The samples were set aside and no further work was done on them for many years. Recently we have resumed work on them and have found that thallium is present in many manganese oxide deposits in the western United States (unpublished data, Hewett, Conklin and Fleischer). The present note gives analyses for four samples from Arizona and two samples from New Mexico, with a discussion of data on thallium in manganese oxides from other localities.