|Latitude & Longitude (WGS84):||41° 28' 59'' North , 73° 24' 29'' West|
|Latitude & Longitude (decimal):||41.48333,-73.40833|
|Locality type:||Mine (Abandoned) - last checked 2018|
|Köppen climate type:||Cfa : Humid subtropical climate|
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):
It did not pan out and is only briefly mentioned in Pulsifer (1888):
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:
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:
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 Plate||Tectonic Plate|
Select Mineral List TypeStandard Detailed Strunz Dana Chemical Elements
Commodity ListThis is a list of exploitable or exploited mineral commodities recorded at this locality.
9 valid minerals. 1 erroneous literature entry.
Detailed Mineral List:
|ⓘ Greenockite ?|
Formula: Zn4Si2O7(OH)2 · H2O
|ⓘ Pyromorphite ?|
List of minerals arranged by Strunz 10th Edition classification
|Group 2 - Sulphides and Sulfosalts|
|Group 5 - Nitrates and Carbonates|
|Group 8 - Phosphates, Arsenates and Vanadates|
|Group 9 - Silicates|
|ⓘ||Hemimorphite ?||9.BD.10||Zn4Si2O7(OH)2 · H2O|
List of minerals arranged by Dana 8th Edition classification
|Group 2 - SULFIDES|
|AmXp, with m:p = 1:1|
|AmBnXp, with (m+n):p = 1:2|
|Group 14 - ANHYDROUS NORMAL CARBONATES|
|Group 41 - ANHYDROUS PHOSPHATES, ETC.CONTAINING HYDROXYL OR HALOGEN|
|Group 56 - SOROSILICATES Si2O7 Groups, With Additional O, OH, F and H2O|
|Si2O7 Groups and O, OH, F, and H2O with cations in  coordination|
|ⓘ||Hemimorphite ?||220.127.116.11||Zn4Si2O7(OH)2 · H2O|
|Group 71 - PHYLLOSILICATES Sheets of Six-Membered Rings|
|Sheets of 6-membered rings with 2:1 layers|
List of minerals for each chemical element
|H||ⓘ Hemimorphite||Zn4Si2O7(OH)2 · H2O|
|O||ⓘ Hemimorphite||Zn4Si2O7(OH)2 · H2O|
|Si||ⓘ Hemimorphite||Zn4Si2O7(OH)2 · H2O|
|Zn||ⓘ Hemimorphite||Zn4Si2O7(OH)2 · H2O|
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
|Precambrian-Phanerozoic sedimentary rocks|
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. 
|Early Ordovician - Cambrian|
470 - 541 Ma
|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
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.