| Main commodities | Ag; Au |
|---|---|
| Other commodities | Cu |
| Ore minerals | arsenopyrite; chalcopyrite |
| Gangue minerals | quartz |
| Quadrangle map, 1:250,000-scale | HE |
|---|---|
| Quadrangle map, 1:63,360-scale | B-6 |
| Latitude | 63.265 |
| Longitude | -149.529 |
| Nearby scientific data | Find additional scientific data near this location |
| Location and accuracy | The Lucrata prospect is at an elevation of about 2,700 feet on the west bank of Costello Creek, about 0.3 mile south of the Dunkle mine camp. It is in sec. 18, T. 19 S., R. 10 W., of the Fairbanks Meridian. Accuracy of location is to within 500 feet. This is locality 2 of Cobb (1978: OFR 78-1062). |
Geologic descriptionThe general area of this prospect is characterized by thick Quaternary glacial deposits and Upper Tertiary sedimentary strata that mostly cover Upper Jurassic to Upper Triassic(?) crystal tuff, argillite, chert, graywacke, and limestone (Wilson and others, 1998). Upper Cretaceous quartz diorite dikes cut the mesozoic bedded rocks, mainly along the nearby Chulitna fault. At the Lucrata prospect, arsenopyrite-chalcopyrite pods up to 4 feet thick and 5 feet long area in a quartz stockwork in gabbro and basalt along the Chulitna fault zone. Assay values as high as 1.26 ounces of gold per ton and 3.8 ounces of silver per ton are reported by Hawley and Clark (1974); average grades of 0.49 ounce of gold per ton and 1.03 ounces of silver per ton are reported by Bundtzen (1983). | |
| Geologic map unit | (-149.531289594792, 63.2645287170485) |
|---|---|
| Mineral deposit model | Polymetallic vein (Cox and Singer, 1986; model 22c) |
| Mineral deposit model number | 22c |
| Age of mineralization | Late Cretaceous or younger, assuming that the deposit is related to the intrusion of the quartz diorite. |
| Alteration of deposit | Quartz-sericite-pyrite alteration. |
| Workings or exploration | There has been both surface and underground exploration; a 15 ft tunnel was driven in 1920. Assay values as high as 1.26 ounces of gold per ton and 3.8 ounces of silver per ton are reported by Hawley and Clark (1974); average grades of 0.49 ounce of gold per ton and 1.03 ounces of silver per ton are reported by Bundtzen (1983). |
|---|---|
| Indication of production | Undetermined |
Additional commentsThe Lucrata prospect has also been referred to as the Dunkle mine. This should be dropped as it invites comparison to the Dunkle coal mine, a separate deposit. | |
| MRDS Number | A011322 |
|---|---|
References | |
| Reporters | N. Van Wyck (Stevens Exploration Management Corporation); F.H. Wilson (USGS) |
| Last report date | 3/28/2016 |