Fortuna Mine (La Fortuna Mine), Barry M. Goldwater Air Force Range, Fortuna Mining District (La Fortuna Mining District), Yuma County, Arizona, USAi
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Latitude & Longitude (WGS84):
32° 33' 6'' North , 114° 19' 48'' West
Latitude & Longitude (decimal):
Type:
Köppen climate type:
Nearest Settlements:
| Place | Population | Distance |
|---|---|---|
| Fortuna Foothills | 26,265 (2011) | 14.1km |
| Wellton | 2,936 (2017) | 21.8km |
| El Prado Estates | 504 (2017) | 24.8km |
| Buckshot | 153 (2017) | 25.4km |
| Rancho Mesa Verde | 625 (2017) | 30.8km |
A former underground Au-Ag-Cu-Fe mine located on 7 original claims plus 5 additional claims when Elan took over operations, in sec. 16 and North-central sec. 21, T.10S., R.20W. (protracted), at the western base of the Gila Mountains, at 775 feet of altitude, about 20 miles from Wellton and 28 miles SE of Yuma, on a military reservation. Started in the early 1890's (1892-1895) and closed in 1904. Reopened 1913-1914 and 1924-1926. Owned at times, or in part, by La Fortuna Gold Mining and Milling Co. Charles D. Lane of Angels Camp (1896- ); Fortuna Mines Corp.; Elan Mining Co. (1924- ); McDaniels & Harrison; Enderton; Holmes & Nichelson; Wish Mining & Milling Co.; Maitland; Messrs. Charles Thomas, William Holbert + 2 others; and, Burton.
The mine is on a narrow, dissected pediment between foothill ridges. The prevailing rocks are Precambrian or later schist and gneiss, intruded by large masses of granite and amphibolite and numerous dikes of pegmatite and aplite. The schist, and part of the gneiss, are of sedimentary origin. These rocks strike West or SW, transverse to the trend of the range, and dip steeply southward. Mineralization is free gold with silver in rounded grains and as thin irregular veinlets with limonite or pyrite, with traces of copper, in fractured quartz in a branching, chimney-like orebody along a fissure zone in Mesozoic schist. The orebody strikes S.40ºW. and dips 70ºSE. It outcrops in 2 branches. One is 20 feet long by 12 feet wide & the other is 30 feet long by 5 feet wide. These join at the 500 level, forming an orebody approximately 100 feet long by 1½ to 12 feet wide. The orebody is lost by fault about 800 from surface and only a small segment was found between the 900 and 1100 levels. Gold-bearing quartz is coarse-grained, vitreous, pale straw-colored & locally stained with malachite. Wall rocks are carbonatized and silicified. There are many branching and intersecting faults.
Workings include 2 inclined shafts connecting with several hundred feet of drifts, stopes, etc. The older, 2-compartment shaft is 350 feet deep & inclines 60º in a N.34ºE. direction. The newer shaft (lower shaft)(1900-1901) is a deep shaft at about 1000 feet deep and inclines 58º in a S.54ºE. direction and was worked mainly from 1896 through 1904, and sporadically thereafter into 1941. A 20-stamp mill was erected on the property. Total estimated and recorded production would be some 213,000 tons of ore averaging about 0.63 oz. Au/T, 0.05 oz. Ag/T, and a few pounds of copper. Assay data: Au averaged $15 to $16 per ton and 890 fine. This equates to $2,587,987 in Au bullion (Sep 1896 - Dec 1904), plus another $25,000 of Au until ultimate closure (period values).
Select Mineral List Type
Standard Detailed Gallery Strunz Chemical ElementsDetailed Mineral List:
| ⓘ Andalusite Formula: Al2(SiO4)O Habit: Prismatic, long, tabular, radiating Description: Occurs as crystals in gray, speckled, quartz-biotite schist adjacent to the vein. |
| ⓘ Epidote Formula: (CaCa)(AlAlFe3+)O[Si2O7][SiO4](OH) Description: Occurs in black schist. |
| ⓘ 'Garnet Group' Formula: X3Z2(SiO4)3 Colour: Brown Description: Occurs as small garnets. |
| ⓘ Hematite Formula: Fe2O3 Description: Occurs as small, shiny masses in schist near its hanging wall. |
| ⓘ Hematite var. Specularite Formula: Fe2O3 Description: Occurs as small, shiny masses in schist near its hanging wall. |
| ⓘ 'Hornblende Root Name Group' Formula: ◻Ca2(Z2+4Z3+)(AlSi7O22)(OH,F,Cl)2 Description: Occurs in vein wall rocks. |
| ⓘ 'Limonite' |
| ⓘ Malachite Formula: Cu2(CO3)(OH)2 Description: Occurs as stains. |
| ⓘ Native Gold Formula: Au Description: Free gold with silver in rounded grains within converging hair-like cracks & as thin, irregular veinlets within limonite or pyrite. |
| ⓘ Pyrite Formula: FeS2 |
Gallery:
List of minerals arranged by Strunz 10th Edition classification
| Group 1 - Elements | |||
|---|---|---|---|
| ⓘ | Native Gold | 1.AA.05 | Au |
| Group 2 - Sulphides and Sulfosalts | |||
| ⓘ | Pyrite | 2.EB.05a | FeS2 |
| Group 4 - Oxides and Hydroxides | |||
| ⓘ | Hematite | 4.CB.05 | Fe2O3 |
| ⓘ | var. Specularite | 4.CB.05 | Fe2O3 |
| Group 5 - Nitrates and Carbonates | |||
| ⓘ | Malachite | 5.BA.10 | Cu2(CO3)(OH)2 |
| Group 9 - Silicates | |||
| ⓘ | Andalusite | 9.AF.10 | Al2(SiO4)O |
| ⓘ | Epidote | 9.BG.05a | (CaCa)(AlAlFe3+)O[Si2O7][SiO4](OH) |
| Unclassified | |||
| ⓘ | 'Limonite' | - | |
| ⓘ | 'Hornblende Root Name Group' | - | ◻Ca2(Z2+4Z3+)(AlSi7O22)(OH,F,Cl)2 |
| ⓘ | 'Garnet Group' | - | X3Z2(SiO4)3 |
List of minerals for each chemical element
| H | Hydrogen | |
|---|---|---|
| H | ⓘ Epidote | (CaCa)(AlAlFe3+)O[Si2O7][SiO4](OH) |
| H | ⓘ Malachite | Cu2(CO3)(OH)2 |
| H | ⓘ Hornblende Root Name Group | ◻Ca2(Z42+Z3+)(AlSi7O22)(OH,F,Cl)2 |
| C | Carbon | |
| C | ⓘ Malachite | Cu2(CO3)(OH)2 |
| O | Oxygen | |
| O | ⓘ Andalusite | Al2(SiO4)O |
| O | ⓘ Epidote | (CaCa)(AlAlFe3+)O[Si2O7][SiO4](OH) |
| O | ⓘ Hematite | Fe2O3 |
| O | ⓘ Malachite | Cu2(CO3)(OH)2 |
| O | ⓘ Hematite var. Specularite | Fe2O3 |
| O | ⓘ Hornblende Root Name Group | ◻Ca2(Z42+Z3+)(AlSi7O22)(OH,F,Cl)2 |
| O | ⓘ Garnet Group | X3Z2(SiO4)3 |
| F | Fluorine | |
| F | ⓘ Hornblende Root Name Group | ◻Ca2(Z42+Z3+)(AlSi7O22)(OH,F,Cl)2 |
| Al | Aluminium | |
| Al | ⓘ Andalusite | Al2(SiO4)O |
| Al | ⓘ Epidote | (CaCa)(AlAlFe3+)O[Si2O7][SiO4](OH) |
| Al | ⓘ Hornblende Root Name Group | ◻Ca2(Z42+Z3+)(AlSi7O22)(OH,F,Cl)2 |
| Si | Silicon | |
| Si | ⓘ Andalusite | Al2(SiO4)O |
| Si | ⓘ Epidote | (CaCa)(AlAlFe3+)O[Si2O7][SiO4](OH) |
| Si | ⓘ Hornblende Root Name Group | ◻Ca2(Z42+Z3+)(AlSi7O22)(OH,F,Cl)2 |
| Si | ⓘ Garnet Group | X3Z2(SiO4)3 |
| S | Sulfur | |
| S | ⓘ Pyrite | FeS2 |
| Cl | Chlorine | |
| Cl | ⓘ Hornblende Root Name Group | ◻Ca2(Z42+Z3+)(AlSi7O22)(OH,F,Cl)2 |
| Ca | Calcium | |
| Ca | ⓘ Epidote | (CaCa)(AlAlFe3+)O[Si2O7][SiO4](OH) |
| Ca | ⓘ Hornblende Root Name Group | ◻Ca2(Z42+Z3+)(AlSi7O22)(OH,F,Cl)2 |
| Fe | Iron | |
| Fe | ⓘ Epidote | (CaCa)(AlAlFe3+)O[Si2O7][SiO4](OH) |
| Fe | ⓘ Hematite | Fe2O3 |
| Fe | ⓘ Pyrite | FeS2 |
| Fe | ⓘ Hematite var. Specularite | Fe2O3 |
| Cu | Copper | |
| Cu | ⓘ Malachite | Cu2(CO3)(OH)2 |
| Au | Gold | |
| Au | ⓘ Native Gold | Au |
Other Databases
| Link to USGS MRDS: | 10027250 |
|---|
Other Regions, Features and Areas containing this locality
North AmericaContinent
- Sonoran DesertDesert
North America PlateTectonic Plate
- Basin and Range BasinsBasin
- Mojave DomainDomain
- Southern Basin and RangeWide Rift
USA
- Arizona
- Yuma County
- Gila Mountains (Western)Mountain Range
- Yuma County
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References
(1933) Geology and Mineral Deposits of Southern Yuma County, Arizona. University of Arizona Bulletin 134. Arizona Bureau of Minespages 43, 189-199
