Maps showing mineralogical data for nonmagnetic heavy-mineral concentrates in the Talkeetna Quadrangle, Alaska
Miscellaneous Field Studies Map
870-I
Left: Map showing the distribution of gold and scheelite. Right: Map showing the distribution of chalcopyrite, arsenopyrite, galena, fluorite, cinnabar, and malachite.
By: R. B. Tripp, R. C. Karlson, and G.C. Curtin
Links
- More information: National Geologic Map Database Index Page (html)
- Download citation as: RIS | Dublin Core
Abstract
Reconnaissance geochemical and mineralogical sampling was done in the Talkeetna Quadrangle during 1975 and 1976 as part of the Alaska Mineral Resource Assessment Program (AMRAP). These maps show the distribution of gold, scheelite, chalcopyrite, arsenopyrite, galena, fluorite, cinnabar, and malachite in the nonmagnetic fraction of heavy-mineral concentrates. Heavy-mineral concentrate samples were collected at 812 sites from active stream channels. The heavy-mineral concentrates were obtained by panning stream sediment in the field to remove most of the light minerals. The panned samples were then sieved through a 20-mesh (0.8 mm) sieve in the laboratory, and the minus-20-mesh fraction was further separated with bromoform (specific gravity, 2.86) to remove any remaining light-mineral grains. Magnetite and other strongly magnetic heavy minerals were removed from the heavy-mineral fraction by use of a hand magnet. The remaining sample was passed through a Frantz Isodynamic Separator and a nonmagnetic fraction was examined for its mineralogical content with the aid of a binocular microscope and an x-ray diffractometer. The nonmagnetic concentrates primarily contain phyllite fragments, muscovite, sphene, zircon, apatite, tourmaline, rutile, and anatase. Most ore and ore-related minerals also occur in this fraction.
Suggested Citation
Tripp, R.B., Karlson, R.C., Curtin, G., 1978, Maps showing mineralogical data for nonmagnetic heavy-mineral concentrates in the Talkeetna Quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map 870, 2 Maps on 1 Sheet: 53.01 x 32 inches, https://doi.org/10.3133/mf870I.
Study Area
| Publication type | Report |
|---|---|
| Publication Subtype | USGS Numbered Series |
| Title | Maps showing mineralogical data for nonmagnetic heavy-mineral concentrates in the Talkeetna Quadrangle, Alaska |
| Series title | Miscellaneous Field Studies Map |
| Series number | 870 |
| Chapter | I |
| DOI | 10.3133/mf870I |
| Year Published | 1978 |
| Language | English |
| Publisher | U.S. Geological Survey |
| Publisher location | Reston, VA |
| Description | 2 Maps on 1 Sheet: 53.01 x 32 inches |
| Time Range Start | 1975-01-01 |
| Time Range End | 1976-12-31 |
| Country | United States |
| State | Alaska |
| Scale | 250000 |