The data release for Gospel-Hump Wilderness Area and the Magruder Corridor and Special Mining Management Zone Additions to the Frank Church River of No Return Wilderness Area, and adjacent areas Idaho and Montana, contains a subset of previously unpublished geochemical data from the 1979-1984 projects. In the case of Gospel-Hump Wilderness Area study (Lund and Esparza, 1990), the purpose of the project was to determine petrologic and geochemical characteristics and to investigate effects of historic mine drainage in the study area. Data for the Magruder Corridor Addition reflect rock geochemistry to document petrologic and geochemical characteristics (Mosier and others, 1981; Lund and others, 1992). Included in this data set are 696 stream sediment samples, 90 magnetic heavy-mineral concentrate samples (C1 fraction) of stream sediment, 256 nonmagnetic heavy-mineral concentrate samples (C3 fraction) of stream sediment, 134 slightly magnetic to nonmagnetic heavy-mineral concentrate samples (C4 fraction) of stream sediment, and 704 rock samples. All were analyzed by semi-quantitative 6-step emission spectrography. Some of the stream sediment samples were also analyzed by flame-atomic absorption spectrophotometry after partial digestion by K2S2O7 fusion, HCl-KI dissolution and extraction with MIBK. Also analyzed with these samples were 99 standard reference material samples (SRMs) and 53 blind SRMs. The data for these standards are not included in this data release. Data for the Special Mining Management Zone Addition are re-analyses of selected stream-sediment samples from earlier studies (Cater and others, 1975; Knowles, 1975) to augment data collected for a study published by Lund and others (1983). For the Special Mining Management Zone, data in this data set were re-analyzed from earlier studies as supplement to samples collected for the study published in Lund and others (1983). Sample numbers (FIELD_ID) beginning with 5FC are selected stream-sediment samples reanalyzed from Cater and others (1975, see their Table 1). Sample numbers (FIELD_ID) beginning with 5K are selected stream-sediment samples reanalyzed from Knowles (1975, their Table 1).