Benjamin Franklin Mine, Chester Springs, West Pikeland Township, Chester County, Pennsylvania, USAi
| Regional Level Types | |
|---|---|
| Benjamin Franklin Mine | Mine (Inactive) |
| Chester Springs | Group of Hamlets |
| West Pikeland Township | Township |
| Chester County | County |
| Pennsylvania | State |
| USA | Country |
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Latitude & Longitude (WGS84):
40° 5' 39'' North , 75° 37' 0'' West
Latitude & Longitude (decimal):
Type:
Mine (Inactive) - last checked 2024
Age:
Up to ~4600 Ma
Geologic Time:
Köppen climate type:
Nearest Settlements:
| Place | Population | Distance |
|---|---|---|
| Chester Springs | 7,520 (2017) | 0.1km |
| Lionville | 6,189 (2017) | 5.8km |
| Eagleview | 1,644 (2017) | 6.7km |
| Exton | 4,842 (2017) | 7.3km |
| Phoenixville | 16,658 (2017) | 9.5km |
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 |
|---|---|---|
| Tuscarora Lapidary Society | Brookhaven, Pennsylvania | 32km |
| Friends of Mineralogy - Pennsylvania Chapter | St. Peters, Pennsylvania | 39km |
| Delaware Mineralogical Society, Inc. | Wilmington, Delaware | 39km |
| Delaware Valley Paleontological Society | Philadelphia, Pennsylvania | 42km |
| Philadelphia Mineralogical Society | Philadelphia, Pennsylvania | 42km |
The mine was originally purchased by the US Government and a mill established on site under the War Production Board in 1942. Following completion of the development, the site was leased to the Benjamin Franklin Mining Co. in 1943, which produced 398 tons of graphite between this site and the Just Mine. In 1946, the North American Graphite Co. leased the mine, producing 120 tons of graphite before shutting down in January 1948.
The US Bureau of Mines surveyed the site in 1948, finding the graphitic zone to contain about 1.5% graphite and the weathering to run as deep as 120 feet. The mine consisted of an open pit, with the one on the Benjamin Franklin property being just northeast of the mill, and was around 240 feet long, 30 to 100 feet wide, and 40 feet deep. A second pit in the Just Mine was described as being larger and closely associated with the Benjamin Franklin Mine.
The graphite is hosted in a mix of micaceous quartz schist, quartzite and feldspathic quartz-muscovite gneiss, with those rocks grading into each other. Pegmatites intruded parallel to the host rock's foliation. The rocks are heavily weathered. Most of the graphite occurs in layers that range from a few inches to more than 10 feet in thickness.
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
5 valid minerals.
Detailed Mineral List:
| ⓘ 'Biotite' Formula: K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2 |
| ⓘ 'Garnet Group' Formula: X3Z2(SiO4)3 |
| ⓘ Goethite Formula: Fe3+O(OH) |
| ⓘ Graphite Formula: C References: |
| ⓘ 'Limonite' Colour: Iridescent Description: Iridescent. References: |
| ⓘ Pyrite Formula: FeS2 |
| ⓘ Quartz Formula: SiO2 Colour: Blue References: |
| ⓘ Zircon Formula: Zr(SiO4) References: |
Gallery:
List of minerals arranged by Strunz 10th Edition classification
| Group 1 - Elements | |||
|---|---|---|---|
| ⓘ | Graphite | 1.CB.05a | C |
| Group 2 - Sulphides and Sulfosalts | |||
| ⓘ | Pyrite | 2.EB.05a | FeS2 |
| Group 4 - Oxides and Hydroxides | |||
| ⓘ | Goethite | 4.00. | Fe3+O(OH) |
| ⓘ | Quartz | 4.DA.05 | SiO2 |
| Group 9 - Silicates | |||
| ⓘ | Zircon | 9.AD.30 | Zr(SiO4) |
| Unclassified | |||
| ⓘ | 'Biotite' | - | K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2 |
| ⓘ | 'Limonite' | - | |
| ⓘ | 'Garnet Group' | - | X3Z2(SiO4)3 |
List of minerals for each chemical element
| H | Hydrogen | |
|---|---|---|
| H | ⓘ Biotite | K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2 |
| H | ⓘ Goethite | Fe3+O(OH) |
| C | Carbon | |
| C | ⓘ Graphite | C |
| O | Oxygen | |
| O | ⓘ Biotite | K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2 |
| O | ⓘ Goethite | Fe3+O(OH) |
| O | ⓘ Quartz | SiO2 |
| O | ⓘ Zircon | Zr(SiO4) |
| O | ⓘ Garnet Group | X3Z2(SiO4)3 |
| F | Fluorine | |
| F | ⓘ Biotite | K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2 |
| Mg | Magnesium | |
| Mg | ⓘ Biotite | K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2 |
| Al | Aluminium | |
| Al | ⓘ Biotite | K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2 |
| Si | Silicon | |
| Si | ⓘ Biotite | K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2 |
| Si | ⓘ Quartz | SiO2 |
| Si | ⓘ Zircon | Zr(SiO4) |
| Si | ⓘ Garnet Group | X3Z2(SiO4)3 |
| S | Sulfur | |
| S | ⓘ Pyrite | FeS2 |
| K | Potassium | |
| K | ⓘ Biotite | K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2 |
| Ti | Titanium | |
| Ti | ⓘ Biotite | K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2 |
| Fe | Iron | |
| Fe | ⓘ Biotite | K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2 |
| Fe | ⓘ Goethite | Fe3+O(OH) |
| Fe | ⓘ Pyrite | FeS2 |
| Zr | Zirconium | |
| Zr | ⓘ Zircon | Zr(SiO4) |
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Benjamin Franklin Mine, Chester Springs, West Pikeland Township, Chester County, Pennsylvania, USA