Mine Mountain graphite prospect, Cornwall, Litchfield County, Connecticut, USAi
| Regional Level Types | |
|---|---|
| Mine Mountain graphite prospect | Prospect |
| Cornwall | - not defined - |
| Litchfield County | County |
| Connecticut | State |
| USA | Country |
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Latitude & Longitude (WGS84):
41° 50' 21'' North , 73° 22' 14'' West
Latitude & Longitude (decimal):
Locality type:
Prospect - last checked 2021
KΓΆppen climate type:
Nearest Settlements:
| Place | Population | Distance |
|---|---|---|
| Sharon | 729 (2017) | 9.8km |
| Falls Village | 538 (2017) | 13.0km |
| Lakeville | 928 (2017) | 15.1km |
| Amenia | 955 (2017) | 15.5km |
| Kent | 2,858 (2017) | 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 |
|---|---|---|
| Bristol Gem & Mineral Club | Bristol, Connecticut | 40km |
| Mid-Hudson Valley Gem and Mineral Society Inc. | Poughkeepsie, New York | 48km |
| Danbury Mineralogical Society | Danbury, Connecticut | 50km |
This is an 18th century locality, with only poor location information in the literature, but as part of a state-wide mine and quarry survey sponsored by the Connecticut Geological Survey it was found on May 22, 2021. Its exact location high on the south-facing slope of graphite-rich, heavily wooded Mine Mountain is consistent with the historical record detailed below. It lies within the Housatonic State Forest.
Noted first by Brace (1819) and referenced by Robinson (1825), Shepard (1837) describes this prospect in more detail:
Another depository of plumbago is in the western part of Cornwall, on a mountain nearly three hundred feet high [it is actually more like 700 feet high], and situated directly upon the eastern bank of the Housatonic river. It is the property of Mr. GIDEON P. PANGMAN. The rock is gneiss, and wherever it comes into view on its western slope, this mineral may be detected as entering more or less into its composition,βsometimes in large proportion (74), forming a plumbaginous gneiss. A trench has been excavated at an elevation of about one hundred and fifty feet above the river [actually about 400 feet], nearly six feet wide and twenty long, into a rock made up of a gray pyroxene, through which large laminae of plumbago are disseminated (369). The cross seams of this bed present a coating of very pure plumbago, about half an inch in thickness. The wide diffusion of the mineral at this place, affords some encouragement that a vein or bed of it fit for working will ultimately be found.
Ed Force (2007) wrote about this old locality:
Graphite was also found on Mine Mountain in West Cornwall, where the mine area was sequestered (reserved as town property) in 1741. Historian Michael Gannett has studied its history, and has told me that after the community failed to make a profit at it, a New York company was allowed to mine it in 1752. This firm sent specimens of the ore to New York and reported that the ore was worth 40 pounds to the tonβyet they couldn't make a profit of it, and people began to suspect that their evaluation was not reliable. So when another company wanted to mine it in 1767, they were turned down. In short, nobody did much actual mining there, and the mines were abandoned - as so often in our state - , leaving a large trench that I hope to find if I ever reach the top of Mine Mountain.
Gold (1904) provides a short summary:
...a considerable excavation was made in the rock [of Mine Mountain] for [graphite], even before the time of the Revolution. The principle vein runs downward and grows narrower, so that although the [graphite] is of excellent quality it cannot be obtained in paying quantities, and after repeated trials at subsequent periods, the search has been abandoned.
Gates (1961) does not explicitly show the prospect, but he describes the Proterozoic quartzo-feldspathic gneiss that encompasses the graphite ore and notes that this "coarse graphite-bearing belt is well exposed on the east and southwest slopes of the triangular peak at the crest of Mine Mountain." He notes that some of the graphite is hosted by diopside-quartz granulite pods of irregular distribution.
Select Mineral List Type
Standard Detailed Gallery Strunz Chemical ElementsDetailed Mineral List:
| β Actinolite Formula: ◻Ca2(Mg4.5-2.5Fe0.5-2.5)Si8O22(OH)2 Habit: elongated prismatic Colour: pale green Description: Masses of bladed crystals Reference: Harold Moritz field observations |
| β Albite Formula: Na(AlSi3O8) Reference: Ed Force collection |
| β Diopside Formula: CaMgSi2O6 Habit: elongated prismatic, square cross-sections Colour: light olive green to gray Description: Granular to elongated crystals in spaces probably from the dissolution of calcite, associated with albite, graphite and titanite. Reference: Harold Moritz field observations |
| β Epidote Formula: {Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH) Description: With kyanite and graphite. Reference: Brace, John P. (1819), Observations on the Minerals Connected with the Gneiss Range of Litchfield County. American Journal of Science: s.1, 1: 351-355.; Robinson, Samuel. (1825), A Catalogue of American Minerals, With Their Localities; Including All Which Are Known to Exist in the United States and British Provinces, And Having the Towns, Counties, and Districts in Each State and Province Arranged Alphabetically. With an Appendix, Containing Additional Localities and a Tabular View. Cummings, Hilliard, & Co., Boston. |
| βͺ Graphite Formula: C Habit: massive to platy, foliated Colour: dark gray to black Description: As masses, isolated or aggregated plates, or veins in quartz or diopside matrix. Reference: Brace, John P. (1819), Observations on the Minerals Connected with the Gneiss Range of Litchfield County. American Journal of Science: s.1, 1: 351-355.; Robinson, Samuel. (1825), A Catalogue of American Minerals, With Their Localities; Including All Which Are Known to Exist in the United States and British Provinces, And Having the Towns, Counties, and Districts in Each State and Province Arranged Alphabetically. With an Appendix, Containing Additional Localities and a Tabular View. Cummings, Hilliard, & Co., Boston. |
| β Kyanite Formula: Al2(SiO4)O Description: With graphite and epidote. Reference: Brace, John P. (1819), Observations on the Minerals Connected with the Gneiss Range of Litchfield County. American Journal of Science: s.1, 1: 351-355.; Robinson, Samuel. (1825), A Catalogue of American Minerals, With Their Localities; Including All Which Are Known to Exist in the United States and British Provinces, And Having the Towns, Counties, and Districts in Each State and Province Arranged Alphabetically. With an Appendix, Containing Additional Localities and a Tabular View. Cummings, Hilliard, & Co., Boston. |
| β Opal Formula: SiO2 · nH2O Reference: Ed Force collection |
| β Opal var. Opal-AN Formula: SiO2 · nH2O Habit: coating Colour: colorless Fluorescence: bright green under SW and MW UV light Description: Thin films invisble except under SW UV light due to bright green fluorescence. Reference: Ed Force collection |
| β Quartz Formula: SiO2 Colour: Milky Description: Massive Reference: Harold Moritz field observations |
| β Titanite Formula: CaTi(SiO4)O Habit: wedges Colour: brown Description: Small crystals associated with diopside or tremolite and graphite. Reference: Harold Moritz field observations |
List of minerals arranged by Strunz 10th Edition classification
| Group 1 - Elements | |||
|---|---|---|---|
| β | Graphite | 1.CB.05a | C |
| Group 4 - Oxides and Hydroxides | |||
| β | Opal | 4.DA.10 | SiO2 Β· nH2O |
| β | var. Opal-AN | 4.DA.10 | SiO2 Β· nH2O |
| β | Quartz | 4.DA.05 | SiO2 |
| Group 9 - Silicates | |||
| β | Actinolite | 9.DE.10 | β»Ca2(Mg4.5-2.5Fe0.5-2.5)Si8O22(OH)2 |
| β | Albite | 9.FA.35 | Na(AlSi3O8) |
| β | Diopside | 9.DA.15 | CaMgSi2O6 |
| β | Epidote | 9.BG.05a | {Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH) |
| β | Kyanite | 9.AF.15 | Al2(SiO4)O |
| β | Titanite | 9.AG.15 | CaTi(SiO4)O |
List of minerals for each chemical element
| H | Hydrogen | |
|---|---|---|
| H | β Epidote | {Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH) |
| H | β Opal | SiO2 · nH2O |
| H | β Opal var. Opal-AN | SiO2 · nH2O |
| H | β Actinolite | ◻Ca2(Mg4.5-2.5Fe0.5-2.5)Si8O22(OH)2 |
| C | Carbon | |
| C | β Graphite | C |
| O | Oxygen | |
| O | β Kyanite | Al2(SiO4)O |
| O | β Epidote | {Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH) |
| O | β Opal | SiO2 · nH2O |
| O | β Diopside | CaMgSi2O6 |
| O | β Titanite | CaTi(SiO4)O |
| O | β Opal var. Opal-AN | SiO2 · nH2O |
| O | β Actinolite | ◻Ca2(Mg4.5-2.5Fe0.5-2.5)Si8O22(OH)2 |
| O | β Albite | Na(AlSi3O8) |
| O | β Quartz | SiO2 |
| Na | Sodium | |
| Na | β Albite | Na(AlSi3O8) |
| Mg | Magnesium | |
| Mg | β Diopside | CaMgSi2O6 |
| Mg | β Actinolite | ◻Ca2(Mg4.5-2.5Fe0.5-2.5)Si8O22(OH)2 |
| Al | Aluminium | |
| Al | β Kyanite | Al2(SiO4)O |
| Al | β Epidote | {Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH) |
| Al | β Albite | Na(AlSi3O8) |
| Si | Silicon | |
| Si | β Kyanite | Al2(SiO4)O |
| Si | β Epidote | {Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH) |
| Si | β Opal | SiO2 · nH2O |
| Si | β Diopside | CaMgSi2O6 |
| Si | β Titanite | CaTi(SiO4)O |
| Si | β Opal var. Opal-AN | SiO2 · nH2O |
| Si | β Actinolite | ◻Ca2(Mg4.5-2.5Fe0.5-2.5)Si8O22(OH)2 |
| Si | β Albite | Na(AlSi3O8) |
| Si | β Quartz | SiO2 |
| Ca | Calcium | |
| Ca | β Epidote | {Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH) |
| Ca | β Diopside | CaMgSi2O6 |
| Ca | β Titanite | CaTi(SiO4)O |
| Ca | β Actinolite | ◻Ca2(Mg4.5-2.5Fe0.5-2.5)Si8O22(OH)2 |
| Ti | Titanium | |
| Ti | β Titanite | CaTi(SiO4)O |
| Fe | Iron | |
| Fe | β Epidote | {Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH) |
| Fe | β Actinolite | ◻Ca2(Mg4.5-2.5Fe0.5-2.5)Si8O22(OH)2 |
References
Sort by
Year (asc) Year (desc) Author (A-Z) Author (Z-A)Brace, John P. (1819) Observations on the Minerals Connected with the Gneiss Range of Litchfield County. American Journal of Science: s.1, 1: 351-355.
Robinson, Samuel. (1825) A Catalogue of American Minerals, With Their Localities; Including All Which Are Known to Exist in the United States and British Provinces, And Having the Towns, Counties, and Districts in Each State and Province Arranged Alphabetically. With an Appendix, Containing Additional Localities and a Tabular View. Cummings, Hilliard, & Co., Boston.
Shepard, Charles U. (1837) Report on the Geological Survey of Connecticut. B. L. Hamlem, New Haven.
Gold, Theodore Sedgewick, ed. (1904) Historical records of the town of Cornwall, Litchfield County, Connecticut. The Case, Lockwood & Brainard company: 20.
Gates, Robert. (1961) The Bedrock Geology of the Cornwall Quadrangle. State Geological and Natural History Survey of Connecticut. Quadrangle Report No. 11.
Force, Ed. (2007) Did Plumbago Get Lumbago. Privately published.
External Links
Other Regions, Features and Areas containing this locality
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Mine Mountain graphite prospect, Cornwall, Litchfield County, Connecticut, USA