Mexican Prospect, Juneau Mining District, Juneau, Alaska, USAi
Regional Level Types | |
---|---|
Mexican Prospect | Prospect |
Juneau Mining District | Mining District |
Juneau | City Borough |
Alaska | State |
USA | Country |
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Latitude & Longitude (WGS84):
58° 52' 1'' North , 135° 5' 20'' West
Latitude & Longitude (decimal):
Type:
Köppen climate type:
Mindat Locality ID:
198853
Long-form identifier:
mindat:1:2:198853:9
GUID (UUID V4):
810ad7cc-e2cc-4dc8-ad17-355365b247a9
Location: The Mexican prospect is at an elevation of about 2,050 feet, 2 miles northeast of Pt. Sherman on Lynn Canal and 1 mile west-southwest of Lions Head Mountain in the Kakuhan Range. It is 1/4 mile NW of the Kensington Mine (JU029) in the NW1/4 section 4, T. 35 S., R. 62 E. of the Copper River Meridian. The location is accurate.
Geology: The Mexican prospect was discovered in 1887 and developed by 2 adits, a 135-foot crosscut, and a 106-foot drift. The deposit consists of a 1- to 8-foot-thick quartz vein, and quartz-vein stockworks in a shear zone in Jualin Diorite. The zone trends northerly and dips 60-84 degrees east. The vein is possibly the same as the principal one at the Horrible Mine (JU027) (Redman and others, 1989). The Mexican deposit is in Coeur Alaska's Kensington project area (see JU029). The Kensington project area, as defined by Coeur, includes the Kensington (JU029), Horrible and other veins, and contains over 1.96 million ounces of proven and probable gold (Bundtzen and others, 1996). The Mexican prospect is in the Kensington project area, that in 2001 was controlled by Coeur Alaska. It is in the Berners Bay district at the north end of the Juneau Gold Belt. The district is characterized by a series of structurally-controlled, mesothermal, gold-bearing quartz veins. Most of the veins are in Early Cretaceous (105 Ma) Jualin Diorite, which intrudes Upper Triassic metabasalt. The Jualin Diorite is generally massive, jointed, blocky, quartz monzonite to quartz monzodiorite. Gold occurs in low-sulfide, quartz-carbonate veins that contain pyrite and tellurides; the veins are marked by distinctive ankeritic alteration zones. There are both extensional and shear veins that generally strike north to northwest and dip east. Discrete vein systems are defined by one or more through-going quartz veins, many of which are in shear zones. Levielle (1991) and Knopf (1911) describe other gangue minerals near vein margins including albite, chlorite, muscovite, and lesser tourmaline, rutile, and apatite. Hydrothermal alteration adjacent to the veins is characterized by reddish-brown ferroan dolomite (Miller and others, 1995). Other alteration includes sericitization of plagioclase, chloritization, sulfidization of mafic minerals, and albitization of feldspars (Leveille, 1991). Pyrite is the most abundant sulfide mineral, with lesser amounts of chalcopyrite, galena, sphalerite, arsenopyrite, and tetrahedrite. Gold occurs in the native state, in pyrite, and in various telluride minerals such as calaverite, hessite, and petzite (Leveille, 1991; Redman and others, 1989). The vein paragenesis consists of early quartz, carbonates, albite and pyrite, followed by deposition of base and precious metals. Gold, galena and the tellurides were the last to be deposited (Leveille, 1991). The age of hydrothermal muscovite from veins at Kensington Mine (JU029) varies from 53.4 Ma to 56.5 Ma (Miller and others, 1994). This coincides with the 55 Ma age of the other mesothermal gold vein deposits in the Juneau Gold Belt (Goldfarb and others, 1997).
Workings: In its early years, the Mexican prospect was developed by 2 adits, a 135-foot crosscut and a 106-foot drift. The deposit has been extensively drilled by Placid Oil Co. and Echo Bay Mines-Coeur Alaska, and is currently (2001) controlled by Coeur Alaska.
Age: The age of mineralization in the Berners Bay district is about 55 Ma, the same as the other mesothermal gold-quartz-vein deposits in the Juneau Gold Belt (Goldfarb and others, 1997).
Alteration: Hydrothermal alteration adjacent to the veins is characterized by reddish-brown ferroan dolomite alteration (Miller and others, 1995). Other alteration includes sericitization of plagioclase, chloritization and sulfidization of mafic minerals, and albitization of feldspars (Leveille, 1991).
Production: No recorded production.
Reserves: The Kensington project area (see JU029), as defined by Coeur, includes the Kensington (JU029), Ophir (JU026), Mexican, Horrible (JU027), and other veins, and contains over 1.96 million ounces of proven and probable gold (Bundtzen and others, 1996).
Commodities (Major) - Au; (Minor) - Ag, Cu, Pb, Zn
Development Status: None
Deposit Model: Low-sulfide Au-quartz vein (Cox and Singer, 1986; model 36a)
Select Mineral List Type
Standard Detailed Gallery Strunz Chemical ElementsCommodity List
This is a list of exploitable or exploited mineral commodities recorded at this locality.Mineral List
16 valid minerals.
Detailed Mineral List:
ⓘ Albite Formula: Na(AlSi3O8) |
ⓘ Ankerite Formula: Ca(Fe2+,Mg)(CO3)2 |
ⓘ 'Apatite' Formula: Ca5(PO4)3(Cl/F/OH) |
ⓘ Arsenopyrite Formula: FeAsS |
ⓘ Calaverite Formula: AuTe2 |
ⓘ Calcite Formula: CaCO3 |
ⓘ Chalcopyrite Formula: CuFeS2 |
ⓘ 'Chlorite Group' |
ⓘ Dolomite Formula: CaMg(CO3)2 |
ⓘ Dolomite var. Iron-bearing Dolomite Formula: Ca(Mg,Fe)(CO3)2 |
ⓘ Galena Formula: PbS |
ⓘ Gold Formula: Au |
ⓘ Hessite Formula: Ag2Te |
ⓘ Muscovite Formula: KAl2(AlSi3O10)(OH)2 |
ⓘ Petzite Formula: Ag3AuTe2 |
ⓘ Pyrite Formula: FeS2 |
ⓘ Quartz Formula: SiO2 |
ⓘ Rutile Formula: TiO2 |
ⓘ Sphalerite Formula: ZnS |
ⓘ 'Tetrahedrite Subgroup' Formula: Cu6(Cu4C2+2)Sb4S12S |
ⓘ 'Tourmaline' Formula: AD3G6 (T6O18)(BO3)3X3Z |
Gallery:
List of minerals arranged by Strunz 10th Edition classification
Group 1 - Elements | |||
---|---|---|---|
ⓘ | Gold | 1.AA.05 | Au |
Group 2 - Sulphides and Sulfosalts | |||
ⓘ | Hessite | 2.BA.60 | Ag2Te |
ⓘ | Petzite | 2.BA.75 | Ag3AuTe2 |
ⓘ | Sphalerite | 2.CB.05a | ZnS |
ⓘ | Chalcopyrite | 2.CB.10a | CuFeS2 |
ⓘ | Galena | 2.CD.10 | PbS |
ⓘ | Calaverite | 2.EA.10 | AuTe2 |
ⓘ | Pyrite | 2.EB.05a | FeS2 |
ⓘ | Arsenopyrite | 2.EB.20 | FeAsS |
ⓘ | 'Tetrahedrite Subgroup' | 2.GB.05 | Cu6(Cu4C2+2)Sb4S12S |
Group 4 - Oxides and Hydroxides | |||
ⓘ | Quartz | 4.DA.05 | SiO2 |
ⓘ | Rutile | 4.DB.05 | TiO2 |
Group 5 - Nitrates and Carbonates | |||
ⓘ | Calcite | 5.AB.05 | CaCO3 |
ⓘ | Dolomite var. Iron-bearing Dolomite | 5.AB.10 | Ca(Mg,Fe)(CO3)2 |
ⓘ | 5.AB.10 | CaMg(CO3)2 | |
ⓘ | Ankerite | 5.AB.10 | Ca(Fe2+,Mg)(CO3)2 |
Group 9 - Silicates | |||
ⓘ | Muscovite | 9.EC.15 | KAl2(AlSi3O10)(OH)2 |
ⓘ | Albite | 9.FA.35 | Na(AlSi3O8) |
Unclassified | |||
ⓘ | 'Tourmaline' | - | AD3G6 (T6O18)(BO3)3X3Z |
ⓘ | 'Chlorite Group' | - | |
ⓘ | 'Apatite' | - | Ca5(PO4)3(Cl/F/OH) |
List of minerals for each chemical element
H | Hydrogen | |
---|---|---|
H | ⓘ Muscovite | KAl2(AlSi3O10)(OH)2 |
H | ⓘ Apatite | Ca5(PO4)3(Cl/F/OH) |
B | Boron | |
B | ⓘ Tourmaline | AD3G6 (T6O18)(BO3)3X3Z |
C | Carbon | |
C | ⓘ Ankerite | Ca(Fe2+,Mg)(CO3)2 |
C | ⓘ Calcite | CaCO3 |
C | ⓘ Dolomite | CaMg(CO3)2 |
C | ⓘ Dolomite var. Iron-bearing Dolomite | Ca(Mg,Fe)(CO3)2 |
O | Oxygen | |
O | ⓘ Albite | Na(AlSi3O8) |
O | ⓘ Ankerite | Ca(Fe2+,Mg)(CO3)2 |
O | ⓘ Calcite | CaCO3 |
O | ⓘ Dolomite | CaMg(CO3)2 |
O | ⓘ Muscovite | KAl2(AlSi3O10)(OH)2 |
O | ⓘ Quartz | SiO2 |
O | ⓘ Rutile | TiO2 |
O | ⓘ Tourmaline | AD3G6 (T6O18)(BO3)3X3Z |
O | ⓘ Dolomite var. Iron-bearing Dolomite | Ca(Mg,Fe)(CO3)2 |
O | ⓘ Apatite | Ca5(PO4)3(Cl/F/OH) |
F | Fluorine | |
F | ⓘ Apatite | Ca5(PO4)3(Cl/F/OH) |
Na | Sodium | |
Na | ⓘ Albite | Na(AlSi3O8) |
Mg | Magnesium | |
Mg | ⓘ Ankerite | Ca(Fe2+,Mg)(CO3)2 |
Mg | ⓘ Dolomite | CaMg(CO3)2 |
Mg | ⓘ Dolomite var. Iron-bearing Dolomite | Ca(Mg,Fe)(CO3)2 |
Al | Aluminium | |
Al | ⓘ Albite | Na(AlSi3O8) |
Al | ⓘ Muscovite | KAl2(AlSi3O10)(OH)2 |
Si | Silicon | |
Si | ⓘ Albite | Na(AlSi3O8) |
Si | ⓘ Muscovite | KAl2(AlSi3O10)(OH)2 |
Si | ⓘ Quartz | SiO2 |
P | Phosphorus | |
P | ⓘ Apatite | Ca5(PO4)3(Cl/F/OH) |
S | Sulfur | |
S | ⓘ Arsenopyrite | FeAsS |
S | ⓘ Chalcopyrite | CuFeS2 |
S | ⓘ Galena | PbS |
S | ⓘ Pyrite | FeS2 |
S | ⓘ Sphalerite | ZnS |
S | ⓘ Tetrahedrite Subgroup | Cu6(Cu4C22+)Sb4S12S |
Cl | Chlorine | |
Cl | ⓘ Apatite | Ca5(PO4)3(Cl/F/OH) |
K | Potassium | |
K | ⓘ Muscovite | KAl2(AlSi3O10)(OH)2 |
Ca | Calcium | |
Ca | ⓘ Ankerite | Ca(Fe2+,Mg)(CO3)2 |
Ca | ⓘ Calcite | CaCO3 |
Ca | ⓘ Dolomite | CaMg(CO3)2 |
Ca | ⓘ Dolomite var. Iron-bearing Dolomite | Ca(Mg,Fe)(CO3)2 |
Ca | ⓘ Apatite | Ca5(PO4)3(Cl/F/OH) |
Ti | Titanium | |
Ti | ⓘ Rutile | TiO2 |
Fe | Iron | |
Fe | ⓘ Ankerite | Ca(Fe2+,Mg)(CO3)2 |
Fe | ⓘ Arsenopyrite | FeAsS |
Fe | ⓘ Chalcopyrite | CuFeS2 |
Fe | ⓘ Pyrite | FeS2 |
Fe | ⓘ Dolomite var. Iron-bearing Dolomite | Ca(Mg,Fe)(CO3)2 |
Cu | Copper | |
Cu | ⓘ Chalcopyrite | CuFeS2 |
Cu | ⓘ Tetrahedrite Subgroup | Cu6(Cu4C22+)Sb4S12S |
Zn | Zinc | |
Zn | ⓘ Sphalerite | ZnS |
As | Arsenic | |
As | ⓘ Arsenopyrite | FeAsS |
Ag | Silver | |
Ag | ⓘ Hessite | Ag2Te |
Ag | ⓘ Petzite | Ag3AuTe2 |
Sb | Antimony | |
Sb | ⓘ Tetrahedrite Subgroup | Cu6(Cu4C22+)Sb4S12S |
Te | Tellurium | |
Te | ⓘ Calaverite | AuTe2 |
Te | ⓘ Hessite | Ag2Te |
Te | ⓘ Petzite | Ag3AuTe2 |
Au | Gold | |
Au | ⓘ Calaverite | AuTe2 |
Au | ⓘ Gold | Au |
Au | ⓘ Petzite | Ag3AuTe2 |
Pb | Lead | |
Pb | ⓘ Galena | PbS |
Other Databases
Link to USGS - Alaska: | JU028 |
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