Bronx Mine (Bronx property; Bronx Copper property), Pinto Creek, Top of the World area, Pinal Mountains Mining District, Pinal Mountains, Gila County, Arizona, USAi
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Latitude & Longitude (WGS84):
33° 21' 57'' North , 110° 58' 33'' West
Latitude & Longitude (decimal):
Type:
KΓΆppen climate type:
Nearest Settlements:
Place | Population | Distance |
---|---|---|
Top-of-the-World | 231 (2011) | 2.4km |
Miami | 1,783 (2017) | 10.6km |
Claypool | 1,538 (2011) | 13.4km |
Superior | 2,943 (2017) | 13.7km |
Central Heights-Midland City | 2,534 (2011) | 15.5km |
Nearest Clubs:
Local clubs are the best way to get access to collecting localities
Local clubs are the best way to get access to collecting localities
Club | Location | Distance |
---|---|---|
Gila County Gem & Mineral Society | Miami, Arizona | 11km |
Mindat Locality ID:
56547
Long-form identifier:
mindat:1:2:56547:6
GUID (UUID V4):
68115797-c7f5-4b86-8b50-75ba1943dc87
A former surface Mo-Ag-Au-Cu-Pb deposit/mine located on 18 claims south-central sec. 6, T1S, R14E (Pinal Ranch 7.5 minute topo map), just N of Top of the World, in the NW part of the Pinal quadrangle, 1ΒΎ miles NE of Pinal Ranch. The property was worked in the 1890's as a high-grade Cu, Ag, Au mine. In 1942, the owner claimed a 12 foot vein in which 7 feet carried 1.04% Mo. Owned by Mr. Frederick Weise (circa WWI). Claims extend into sec. 7.
Mineralization is a replacement deposit. Several mineralizaed veins/fractures that crop out in Schultze granite near the western edge of the stock. They were formed by replacement of the granite. The mineral assemblage of these veins is unlike that of any of the other deposits of the district, but it has characteristics that suggest a relationship to the quartz-muscovite veinlets that occur throughout the most prominent set of joints of the Schultze granite, and they are like the Swede and Clark deposits except that no tungsten minerals have been recognized and molybdenite is present in greater abundance. The veins are widest and most strongly mineralized at the bottom of the canyon, suggesting that the outcrops are near the upper limits of mineralization. Ore occurs in stringers to 3 feet wide zones.
The vein fractures strike NE and dip 60 to 80SE, approximately parallel to the general strike of the muscovite-bearing joints, but they are perhaps a little stronger and more persistent than most joints of the set. The veins are exposed in a deep rugged canyon tributary to Pinto Creek, which is about 4,000 feet to the NE. The outcrop of one vein can be followed for about 1,000 feet, but the others cannot be traced for more than 100 to 200 feet. The veins range in size from stringers and inch or two wide to irregular, partly replaced zones as much as 3 feet wide. They are widest and most strongly mineralized near the bottom of the canyon.
The granite wallrock of the fractures is replaced mainly by quartz and muscovite. Where mineralization was strongest, the middle part of each vein is mostly quartz intergrown with coarse muscovite and containing small masses and scattered grains of pyrite and chalcopyrite. Outward from the middle part the vein commonly grades into loose, porous aggregates of coarse muscovite containing occasional grains and small masses of purple or colorless fluorite. Clots and thin sheaves of molybdenite flakes are abundant in the transition zone between the middle part of the vein and the muscovite envelope. In some places, muscovite aggregates form lenticular masses 2 or 3 feet thick that commonly contain narrow, vug-like masses of quartz intergrown with muscovite and molybdenite and with euhedral quartz filling the central part. The molybdenite is generally associated with quartz; but in some places, coarse flakes of molybdenite are intergrown with flakes of muscovite several inches from the quartz masses.
In the oreshoot that was mined molybdenite occurs as irregular foliated masses as much as 2 inches (5 cm) across in the outer parts of the central quartz core, as coarse flakes in the inner parts of the greisen envelope, and as selvages along many quartz veinlets traversing the less completely replaced granite on the hanging wall side of the quartz core.
The Bronx deposits crop out well within the granite stock and therefore probably were formed in a higher temperature zone than the wolframite veins at the edges of the mass.
Workings include 3 tunnels, one of which was caved in 1939. Production was some 50 tons of high-grade molybdenite ore from one oreshoot during the early days of WWI, consigned to the German government, but never shipped since the stockpile was swept away by a flash flood. Claimed to have produced $60,000 in Au (period values - $35.00 per Troy oz.).
1935 assay data: $11.20 Au $27.80 Ag, $11.70 Cu (6.5%) (period values) Another sample had 1.77-5% Mo.
Select Mineral List Type
Standard Detailed Gallery Strunz Chemical ElementsDetailed Mineral List:
β Chalcocite Formula: Cu2S |
β Chalcopyrite Formula: CuFeS2 |
β Ferrimolybdite Formula: Fe2(MoO4)3 · nH2O |
β Fluorite Formula: CaF2 Colour: Purple, colorless Description: Minute crystals and small masses disseminated in greisen associated with quartz-molybdenite veins. |
β Malachite Formula: Cu2(CO3)(OH)2 |
β Molybdenite Formula: MoS2 Description: Chief sulfide of this deposit; in quartz veins associated with fluorite. |
β Muscovite Formula: KAl2(AlSi3O10)(OH)2 Description: In thin veinlets of cross-oriented muscovite in the coarse-grained greisen associated with the molybdenite-bearing areas of the Schultze granite. |
β Pyrite Formula: FeS2 |
Gallery:
List of minerals arranged by Strunz 10th Edition classification
Group 2 - Sulphides and Sulfosalts | |||
---|---|---|---|
β | Chalcocite | 2.BA.05 | Cu2S |
β | Chalcopyrite | 2.CB.10a | CuFeS2 |
β | Molybdenite | 2.EA.30 | MoS2 |
β | Pyrite | 2.EB.05a | FeS2 |
Group 3 - Halides | |||
β | Fluorite | 3.AB.25 | CaF2 |
Group 5 - Nitrates and Carbonates | |||
β | Malachite | 5.BA.10 | Cu2(CO3)(OH)2 |
Group 7 - Sulphates, Chromates, Molybdates and Tungstates | |||
β | Ferrimolybdite | 7.GB.30 | Fe2(MoO4)3 Β· nH2O |
Group 9 - Silicates | |||
β | Muscovite | 9.EC.15 | KAl2(AlSi3O10)(OH)2 |
List of minerals for each chemical element
H | Hydrogen | |
---|---|---|
H | β Ferrimolybdite | Fe2(MoO4)3 · nH2O |
H | β Malachite | Cu2(CO3)(OH)2 |
H | β Muscovite | KAl2(AlSi3O10)(OH)2 |
C | Carbon | |
C | β Malachite | Cu2(CO3)(OH)2 |
O | Oxygen | |
O | β Ferrimolybdite | Fe2(MoO4)3 · nH2O |
O | β Malachite | Cu2(CO3)(OH)2 |
O | β Muscovite | KAl2(AlSi3O10)(OH)2 |
F | Fluorine | |
F | β Fluorite | CaF2 |
Al | Aluminium | |
Al | β Muscovite | KAl2(AlSi3O10)(OH)2 |
Si | Silicon | |
Si | β Muscovite | KAl2(AlSi3O10)(OH)2 |
S | Sulfur | |
S | β Chalcopyrite | CuFeS2 |
S | β Chalcocite | Cu2S |
S | β Molybdenite | MoS2 |
S | β Pyrite | FeS2 |
K | Potassium | |
K | β Muscovite | KAl2(AlSi3O10)(OH)2 |
Ca | Calcium | |
Ca | β Fluorite | CaF2 |
Fe | Iron | |
Fe | β Chalcopyrite | CuFeS2 |
Fe | β Ferrimolybdite | Fe2(MoO4)3 · nH2O |
Fe | β Pyrite | FeS2 |
Cu | Copper | |
Cu | β Chalcopyrite | CuFeS2 |
Cu | β Chalcocite | Cu2S |
Cu | β Malachite | Cu2(CO3)(OH)2 |
Mo | Molybdenum | |
Mo | β Ferrimolybdite | Fe2(MoO4)3 · nH2O |
Mo | β Molybdenite | MoS2 |
Other Databases
Link to USGS MRDS: | 10027088 |
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Other Regions, Features and Areas containing this locality
North America
- Sonoran DesertDesert
North America PlateTectonic Plate
- Basin and Range BasinsBasin
- Mazatzal DomainDomain
USA
- Arizona
- Tonto National ForestForest
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