Fat Jack Mine, Lane Mountain, Crown King, Pine Grove District, Bradshaw Mts (Bradshaw Range), Yavapai Co., Arizona, USA
|Latitude & Longitude (WGS84):||34° 9' 35'' North , 112° 19' 23'' West|
|Latitude & Longitude (decimal):||34.15972,-112.32306|
A former surface and underground Au-Ag-Amethyst mine located South of Crown King. Claim extends into the E½SE¼SE¼ of sec. 35.
Please note this locality is currently (October 2013) under claim and trespassing and collecting without permission are prohibited.
21 valid minerals.
This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.
Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org
1600 - 2500 Ma
|Crazy Basin Granite|
Age: Proterozoic (1600 - 2500 Ma)
Description: Medium- to coarse-grained, equigranular to porphyritic biotite-muscovite granite (Anderson and Blacet, 1972b, c). Redescribed herein from Crazy Basin Quartz Monzonite (Anderson and Blacet, 1972c), based on chemical composition. Large pluton exposed from south of Cleator to past southern boundary of map area. Cuts Humbug Creek Granodiorite (unit Xhc). In southern two-thirds of outcrop, the medium-fine-grained granite has a strongly developed flow foliation that parallels metawacke (unit Xw) and metapelite (unit Xp). Southern Bradshaw Mountains migmatite complex of Anderson (1989b) equivalent to southern two-thirds of granite. In northern one-third of outcrop, medium- to coarse-grained granite is undeformed to mildly deformed and has domed the metawacke and metapelite (Blacet, 1985). Linear, north-south outcrop pattern of metasedimentary and metavolcanic rocks on east side of pluton related to diapiric rise and uplift of pluton following emplacement. The belt of metavolcanic and metasedimentary rocks is not herein interpreted as a crustal boundary (Leighty and others, 1991). Residual gravity contours cross-cut contact of Crazy Basin Granite with wacke (Leighty and others, 1991), suggesting that southern part of Crazy Basin Granite may overhang northeast-striking metavolcanic and metasedimentary rocks at depth and be rootless. Pluton is more mafic to south, but all is alkali-calcic, mildly to strongly peraluminous, sodic to average in K/Na ratio, and ranges widely in Fe/Mg ratio. Most mafic rocks are very Mg rich and most felsic rocks are very Fe rich. Age 1,695 Ma (S.A. Bowring, unpub. U-Pb zircon data, cited in Karlstrom and others, 1987). 40Ar/39Ar muscovite and biotite dates of 1,410 and 1,412 Ma suggest Middle Proterozoic thermal pulse or protracted cooling (Hodges and Bowring, 1995)
Reference: DeWitt, E., V. Langenheim, E. Force, R.K. Vance, P.A. Lindberg, R.L. Driscoll. Geologic map of the Prescott National Forest and the headwaters of the Verde River, Yavapai and Coconino Counties, Arizona. Scientific Investigations Map SIM-2996. 
1600 - 1800 Ma
|Early Proterozoic granitic rocks|
Age: Statherian (1600 - 1800 Ma)
Description: Wide variety of granitic rocks, including granite, granodiorite, tonalite, quartz diorite, diorite, and gabbro. These rocks commonly are characterized by steep, northeast-striking foliation. (1600-1800 Ma)
Comments: ~ 1.6 - 1.8 Ga
Reference: Horton, J.D., C.A. San Juan, and D.B. Stoeser. The State Geologic Map Compilation (SGMC) geodatabase of the conterminous United States. doi: 10.3133/ds1052. U.S. Geological Survey Data Series 1052. 
Modreski, P.J. & J.A. Scovil (1990), Stolzite, wulfenite's hidden brother: Occurrence at the Fat Jack gold mine, Yavapai County, Arizona (abstract), Mineralogical Record: 21: 99-100.
Scovil, J.A. & L. Wagner, Jr. (1991), The Fat Jack Mine, Yavapai County, Arizona. Mineralogical Record: 22: 21-28.
Anthony, J.W., et al (1995), Mineralogy of Arizona, 3rd.ed.: 319, 344, 348, 384, 426.
USGS Crown King Quadrangle map.
Arizona Department of Mineral Resources Fat Jack group file.
MRDS database Dep. ID #10100849, MRDS ID #TC38951; and, Dep. ID #10259463, MAS ID #0040250722.