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Old lead mine, Brookfield, Fairfield Co., Connecticut, USAi
Regional Level Types
Old lead mineMine (Abandoned)
Brookfield- not defined -
Fairfield Co.County
ConnecticutState
USACountry

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Key
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Latitude & Longitude (WGS84): 41° 28' 59'' North , 73° 24' 29'' West
Latitude & Longitude (decimal): 41.48333,-73.40833
GeoHash:G#: dr7gcxc9v
Locality type:Mine (Abandoned) - last checked 2018
Köppen climate type:Cfa : Humid subtropical climate
Nearest Settlements:
PlacePopulationDistance
New Fairfield14,126 (2017)6.7km
New Milford6,523 (2017)10.4km
Danbury84,657 (2017)10.5km
Newtown1,967 (2017)11.7km
Putnam Lake3,844 (2017)11.7km


A very old lead mine, Januzzi (1976 and 1994) claims it is the country's oldest, but provides no evidence for this. It is a rather obscure place that does not appear in any collecting guidebooks and that Schairer (1931) noted "Produced some very interesting minerals at one time. The locality is now overgrown and difficult to find. Galena and sphalerite in limestone may still be found there." The only real description comes from Shepard (1837):

The more recent discovery of galena in Brookfield excited for a time, sanguine expectations of a valuable lead-mine. The examinations which have been made however, seem to prove that the ore, instead of occupying a continuous bed or vein, is rather disseminated either in small bunches or in a net-work of little veins. The rock containing the ore is white limestone, occasionally dolomitic, which in some places abounds in quartz. With the galena is associated blende..., whose surface very rarely presents small crystals of white lead-ore. Calamine and pyromorphite are also found here. Many good mines of lead have been opened in other countries under less favorable auspices than are presented by this place. The main bunch of ore was indeed exhausted very soon; but slender threads, or leadings as they are called are left, which if followed will very likely conduct to richer repositories. Indeed the nature of the containing rock as well as that of the immediate vicinity, which for a considerable district (one or two miles in extent with a considerable breadth) is chiefly pure limestone though in a dolomitic country, affords much encouragement to the idea of a valuable mining district.


It did not pan out and is only briefly mentioned in Pulsifer (1888):

Galena occurs in Brookfield, Conn., where a mine was opened previous to 1850; but the deposit, though rich in quality proved insufficient in quantity to pay for working.


All subsequent writers essentially paraphrase Shepard or list the minerals he notes from there. However, Shepard's use of the term "calamine" lead to confusion between smithsonite and hemimorphite by subsequent writers like Schrader, Stone and Sanford (1917), Schairer (1931), Januzzi (1959) and Schooner (1961) who call it hemimorphite. However, a full reading of Shepard (1837) reveals this passage:

Calamine.—It is a carbonate of zinc, consisting of oxide of zinc 65, and carbonic acid 35. It usually occurs massive, and often in a friable or earthy condition. Sometimes however, it assumes a stalactitic shape, with rough, corroded surfaces. Its ordinary color is white. It is much valued in the manufacture of brass. The only locality in the State is at Brookfield, where it occurs in white limestone...along with blende and galena.


Elsewhere he describes it as "in the state of an impalpable powder of a white color, and in cellular, bone-like masses accompanies the blende and galena of Brookfield" and "Pulverulent; white. Associated with blende and calcareous spar."

On the other hand he discusses what is now called hemimorphite as “electric calamine” and mentions its occurrence in the local iron blast furnace chimneys, but not at the Brookfield mine. He notes its silica and water content, which clearly distinguishes it from smithsonite.

Also potentially confusing is his term "white lead ore", which could be anglesite or cerussite, but considering that the ore is hosted in marble, the latter seems most likely. He says it was "noticed only in a few small crystals".

Yet somehow Schairer (1931) transmogrified this into his entry for "calamine (hemimorphite) Found in good crystals formerly at the old lead mine southeast of Brookfield." None of which is correct according to Shepard (1837). Thus Januzzi (1959) paraphrased it to "Hemimorphite has been found, in the past, as crystals of fair quality at the old lead mine, southeast of Brookfield." And similarly Schooner (1961): "This mineral came from the old lead mine in Brookfield, in rather good specimens" though he admits "the author has seen none of the material" and according to Shepard (1837) he never would have!

The only new information since Shepard (1837) comes from Januzzi (1994) as a result of the Brookfield bypass section of the U. S. Route 7 expressway construction:

Construction on route 7 north of Danbury exposed an adit of the famous old lead mines southeast of Brookfield, as a result very rich specimens of greenockite were found as well as notable amounts of galena and sphalerite.


Based on a photo in Januzzi (1994), the "greenockite" is little more than thin yellow-green coatings, which appear similar to Shepard's (1837) pyromorphite description as "Pulverulent. Yellowish green". So which mineral is it? Analyses appear necessary.

Specimens recovered around Route 7 construction time consist of brecciated matrix (the ore body is clearly a brittle fault zone, one of many similar ones in western Connecticut) rich in talc from hydrothermal alteration, with disseminated veinlets of calcite, galena, sphalerite and pyrite with yellowish, supposed greenockite coatings.

Regions containing this locality

North America PlateTectonic Plate

Select Mineral List Type

Standard Detailed Strunz Dana Chemical Elements

Commodity List

This is a list of exploitable or exploited mineral commodities recorded at this locality.


Mineral List


9 valid minerals. 1 erroneous literature entry.

Detailed Mineral List:

Calcite
Formula: CaCO3
Cerussite
Formula: PbCO3
Galena
Formula: PbS
Greenockite ?
Formula: CdS
Hemimorphite
Formula: Zn4Si2O7(OH)2 · H2O
Pyrite
Formula: FeS2
Pyromorphite ?
Formula: Pb5(PO4)3Cl
Smithsonite
Formula: ZnCO3
Sphalerite
Formula: ZnS
Talc
Formula: Mg3Si4O10(OH)2

List of minerals arranged by Strunz 10th Edition classification

Group 2 - Sulphides and Sulfosalts
Galena2.CD.10PbS
Greenockite ?2.CB.45CdS
Pyrite2.EB.05aFeS2
Sphalerite2.CB.05aZnS
Group 5 - Nitrates and Carbonates
Calcite5.AB.05CaCO3
Cerussite5.AB.15PbCO3
Smithsonite5.AB.05ZnCO3
Group 8 - Phosphates, Arsenates and Vanadates
Pyromorphite ?8.BN.05Pb5(PO4)3Cl
Group 9 - Silicates
Hemimorphite ?9.BD.10Zn4Si2O7(OH)2 · H2O
Talc9.EC.05Mg3Si4O10(OH)2

List of minerals arranged by Dana 8th Edition classification

Group 2 - SULFIDES
AmXp, with m:p = 1:1
Galena2.8.1.1PbS
Greenockite ?2.8.7.2CdS
Sphalerite2.8.2.1ZnS
AmBnXp, with (m+n):p = 1:2
Pyrite2.12.1.1FeS2
Group 14 - ANHYDROUS NORMAL CARBONATES
A(XO3)
Calcite14.1.1.1CaCO3
Cerussite14.1.3.4PbCO3
Smithsonite14.1.1.6ZnCO3
Group 41 - ANHYDROUS PHOSPHATES, ETC.CONTAINING HYDROXYL OR HALOGEN
A5(XO4)3Zq
Pyromorphite ?41.8.4.1Pb5(PO4)3Cl
Group 56 - SOROSILICATES Si2O7 Groups, With Additional O, OH, F and H2O
Si2O7 Groups and O, OH, F, and H2O with cations in [4] coordination
Hemimorphite ?56.1.2.1Zn4Si2O7(OH)2 · H2O
Group 71 - PHYLLOSILICATES Sheets of Six-Membered Rings
Sheets of 6-membered rings with 2:1 layers
Talc71.2.1.3Mg3Si4O10(OH)2

List of minerals for each chemical element

HHydrogen
H TalcMg3Si4O10(OH)2
H HemimorphiteZn4Si2O7(OH)2 · H2O
CCarbon
C SmithsoniteZnCO3
C CerussitePbCO3
C CalciteCaCO3
OOxygen
O SmithsoniteZnCO3
O CerussitePbCO3
O CalciteCaCO3
O TalcMg3Si4O10(OH)2
O PyromorphitePb5(PO4)3Cl
O HemimorphiteZn4Si2O7(OH)2 · H2O
MgMagnesium
Mg TalcMg3Si4O10(OH)2
SiSilicon
Si TalcMg3Si4O10(OH)2
Si HemimorphiteZn4Si2O7(OH)2 · H2O
PPhosphorus
P PyromorphitePb5(PO4)3Cl
SSulfur
S SphaleriteZnS
S GalenaPbS
S PyriteFeS2
S GreenockiteCdS
ClChlorine
Cl PyromorphitePb5(PO4)3Cl
CaCalcium
Ca CalciteCaCO3
FeIron
Fe PyriteFeS2
ZnZinc
Zn SmithsoniteZnCO3
Zn SphaleriteZnS
Zn HemimorphiteZn4Si2O7(OH)2 · H2O
CdCadmium
Cd GreenockiteCdS
PbLead
Pb GalenaPbS
Pb CerussitePbCO3
Pb PyromorphitePb5(PO4)3Cl

Regional Geology

This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.

Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org

Ordovician - Neoproterozoic
443.8 - 1000 Ma



ID: 3190671
Precambrian-Phanerozoic sedimentary rocks

Age: Neoproterozoic to Ordovician (443.8 - 1000 Ma)

Lithology: Mudstone-carbonate-sandstone-conglomerate

Reference: Chorlton, L.B. Generalized geology of the world: bedrock domains and major faults in GIS format: a small-scale world geology map with an extended geological attribute database. doi: 10.4095/223767. Geological Survey of Canada, Open File 5529. [154]

Early Ordovician - Cambrian
470 - 541 Ma



ID: 2980844
Stockbridge Marble (Including Inwood Marble)

Age: Paleozoic (470 - 541 Ma)

Stratigraphic Name: Stockbridge Marble

Description: White to gray, massive to layered marble, generally dolomitic but containing calcite marble in upper part, locally interlayered with schist or phyllite and with calcareous siltstone or sandstone.

Comments: Part of Western Uplands; Proto-North American (Continental) Terrane - Carbonate Shelf Original map source: Connecticut Geological and Natural History Survey, DEP, in cooperation with the U.S. Geological Survey, 2000, Bedrock Geology of Connecticut, shapefile, scale 1:50,000

Lithology: Major:{marble}, Incidental:{schist, phyllite, siltstone, sandstone}

Reference: Horton, J.D., C.A. San Juan, and D.B. Stoeser. The State Geologic Map Compilation (SGMC) geodatabase of the conterminous United States. doi: 10.3133/ds1052. U.S. Geological Survey Data Series 1052. [133]

Data and map coding provided by Macrostrat.org, used under Creative Commons Attribution 4.0 License

References

Sort by

Year (asc) Year (desc) Author (A-Z) Author (Z-A)
Shepard, Charles U. (1837), A Report on the Geological Survey of Connecticut. Hamlen, New Haven.
Pulsifer, William H. (1888), Notes for a History of Lead (NY, Van Rostrand): 78.
Schrader, Frank C., Stone, Ralph W., and Sanford, Samuel. (1917), Useful Minerals of the United States. U. S. Geological Survey Bulletin 624: 97-101.
Schairer, J. F. (1931), The Minerals of Connecticut. State Geological and Natural History Survey, Hartford Connecticut Bulletin 51.
Januzzi, Ronald E. (1959), The Minerals of Western Connecticut and Southeastern New York State. The Mineralogical Press, Danbury, Connecticut.
Schooner, Richard. (1961), The Mineralogy of Connecticut. Fluorescent House, Branford, Connecticut.
Januzzi, Ronald E. (1976), Mineral Localities of Connecticut and Southeastern New York State. The Mineralogical Press, Danbury, Connecticut.
Januzzi, Ronald E. (1994), Mineral Data Book - Western Connecticut and Environs. The Mineralogical Press, Danbury, Connecticut.


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