Midnight Test Mine (National Gold Mine; Patented claims MS 1535), Spruce Mountain, Groom Creek Mining District, Bradshaw Mountains (Bradshaw Range), Yavapai County, Arizona, USAi
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Latitude & Longitude (WGS84):
34° 28' 25'' North , 112° 24' 5'' West
Latitude & Longitude (decimal):
Type:
Köppen climate type:
Nearest Settlements:
| Place | Population | Distance |
|---|---|---|
| Prescott | 41,899 (2017) | 9.6km |
| Dewey-Humboldt | 3,894 (2011) | 15.9km |
| Prescott Valley | 42,197 (2017) | 17.1km |
| Mayer | 1,497 (2011) | 17.4km |
| Wilhoit | 868 (2011) | 17.8km |
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 |
|---|---|---|
| Prescott Gem & Mineral Club | Prescott Valley, Arizona | 17km |
| Mingus Gem & Mineral Club | Cottonwood, Arizona | 46km |
| Verde River Rockhounds | Cottonwood, Arizona | 46km |
A former underground Au-Ag-Pb-Cu-Zn mine located high up near the Groom Creek - Walker divide on the NW slope of Spruce Mountain at 7,000 feet of altitude. Started about 1902 and produced until 1935. Owned by the National Gold Corp.
Mineralization is a near-surface small oreshoot rich in silver ore hosted in the Green Gulch Volcanics. The vein is 2 feet wide in schist and is irregular to lenticular and generally narrow comprised of coarse-grained, drusy quartz. Ore control was faulting, igneous activity (especially dike emplacement). Concentration was oxidation at near surface. The silicified schist is intruded by stocks & dikes of granodiorite and diorite.
Area structures include veins parallel to the foliation and crosscut it by 10-20 degrees, trending N20E to N-S. The foliation in Precambrian rocks trends N10E to N20E.
Workings include development to the 400 level with a shaft of that depth (before 1906) and to 600 feet deep by 1906. Production reported at $100,000 (period values).
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
6 valid minerals.
Detailed Mineral List:
| ⓘ Galena Formula: PbS Description: Scattered kernels. |
| ⓘ Hematite Formula: Fe2O3 |
| ⓘ 'Limonite' |
| ⓘ Native Gold Formula: Au |
| ⓘ Pyrite Formula: FeS2 Description: BAnds and scattered bunches mainly below the 300 level. |
| ⓘ Quartz Formula: SiO2 Description: Coarse-grained, drusy. |
| ⓘ Sphalerite Formula: ZnS Description: Minor amounts. |
Gallery:
List of minerals arranged by Strunz 10th Edition classification
| Group 1 - Elements | |||
|---|---|---|---|
| ⓘ | Native Gold | 1.AA.05 | Au |
| Group 2 - Sulphides and Sulfosalts | |||
| ⓘ | Sphalerite | 2.CB.05a | ZnS |
| ⓘ | Galena | 2.CD.10 | PbS |
| ⓘ | Pyrite | 2.EB.05a | FeS2 |
| Group 4 - Oxides and Hydroxides | |||
| ⓘ | Hematite | 4.CB.05 | Fe2O3 |
| ⓘ | Quartz | 4.DA.05 | SiO2 |
| Unclassified | |||
| ⓘ | 'Limonite' | - | |
List of minerals for each chemical element
| O | Oxygen | |
|---|---|---|
| O | ⓘ Hematite | Fe2O3 |
| O | ⓘ Quartz | SiO2 |
| Si | Silicon | |
| Si | ⓘ Quartz | SiO2 |
| S | Sulfur | |
| S | ⓘ Galena | PbS |
| S | ⓘ Pyrite | FeS2 |
| S | ⓘ Sphalerite | ZnS |
| Fe | Iron | |
| Fe | ⓘ Hematite | Fe2O3 |
| Fe | ⓘ Pyrite | FeS2 |
| Zn | Zinc | |
| Zn | ⓘ Sphalerite | ZnS |
| Au | Gold | |
| Au | ⓘ Native Gold | Au |
| Pb | Lead | |
| Pb | ⓘ Galena | PbS |
Other Regions, Features and Areas containing this locality
North AmericaContinent
North America PlateTectonic Plate
- Basin and Range BasinsBasin
- Great Plains DomainDomain
- Southern Basin and RangeWide Rift
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