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Hart's Lead Mine, Berlin, Hartford Co., Connecticut, USAi
Regional Level Types
Hart's Lead MineMine (Built Over)
Berlin- not defined -
Hartford Co.County
ConnecticutState
USACountry

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Latitude & Longitude (WGS84): 41° 37' 55'' North , 72° 46' 11'' West
Latitude & Longitude (decimal): 41.63216,-72.76983
GeoHash:G#: drkkb4fsu
Locality type:Mine (Built Over) - last checked 2019
Köppen climate type:Dfa : Hot-summer humid continental climate
Nearest Settlements:
PlacePopulationDistance
Kensington8,459 (2017)0.4km
New Britain72,808 (2017)3.3km
Newington30,562 (2017)8.2km
Plainville17,328 (2017)8.7km
Meriden59,988 (2017)10.9km


An old Revolutionary War lead mine in a fault-hosted hydrothermal vein cutting vesicular Jurassic Hampden Basalt. The galena-rich vein (and others) was exposed in a gorge cut through a minor basalt ridge by the Mattabasset River. It is one of many such fault-hosted veins well-known in the general New Britain area since the construction of state Route 72/9 in the 1980s. James Percival (1822) provided this good description of the galena, sphalerite, baryte, quartz, calcite and bitumen (then thought to be coal) found at this site (at that time a rare exposure) and since in very similar modes throughout the New Britain area. The map he refers to is here: https://www.mindat.org/photo-930803.html

I have designed this article as a brief notice of the locality of the Sulphate of Barytes; I shall therefore dismiss more general observations. The sulphate is found in a vein, perhaps two or three feet wide, in a ridge of green-stone. I have subjoined a rude outline of the vicinity. The ridge of green-stone in which this vein is situated, sinks on its eastern side below the general level, and is fronted by a wall of sand-stone at the distance of three or four rods. It contains three interesting localities. (A) the Barytes vein; (C) the coal-mine, and (D) the lead mine
—(A) the vein of Barytes. This is in the bed of a brook, where it passes in a deep ravine through the green-stone ridge, directly below a mill-dam. The ravine is divided by two masses of rock, so that there are three dams. The north turns a grist-mill; the middle an oil-mill; and the south a saw-mill. At the bottom of the ravine the three channels unite, and pass under two bridges almost contiguous. The vein appears first in the bed of the south channel, just below the saw-mill; it is there traceable north by east about a rod. It is again discoverable about four rods north, in the bed of the stream below the upper bridge. Both of these points are on the same line. The vein is two or three feet wide; its surface is iron brown, and tarnished; but on breaking it, it appears of an opake [sic] pearly white. It is foliated, and breaks into rhomboidal fragments; it is very brittle, which renders it very difficult to detach it in large masses; it often assumes on its surface the appearance of coxcomb spar. I have found fragments of it in the brook below, imbedding crystals of Galena. Parallel with it, and separated by a narrow partition of green-stone, is a thin vein of carbonate of lime foliated, and transparent in fragments. The hyaline appearance of the carbonate easily distinguishes it from the pearly hue of the sulphate. The eastern wall of the ravine projects over, and forms a recess near the upper point of the vein; the ceiling of this recess is covered with minute effervescing stalactites. Directly south of the vein the green-stone rock has been torn away, and its fragments are full of geodes of quartz crystals, often taking the form of hollow cylinders lined with crystals. A little farther south is a large rolled rock of granite; on the surface, (C) the coal-mine. This has been opened on either side of the brook, where it passes through a narrow ridge of green-stone. The coal has been found only in the green-stone. Directly fronting this rock, on the east, is a wall of sand-stone slate, at the base of which the brook runs. The coal was first found, and wrought, in the bed of the brook, about twenty years ago; about six years ago, a company in New-York made new openings in either bank of the brook. The coal is found in veins in connection with crystallized quartz; the quartz often appears in geodes whose cavities are filled with coal; narrow veins have their walls lined with crystallized plates of quartz, and are filled with coal; the coal has never been found in large masses: the largest that I have seen not more than two or three pounds. The larger masses are foliated, shining, brittle, and very bituminous; but it more usually has the appearance of cinders so mixed up with silicious matter as to be hardly combustible. The sand-stone in its vicinity I have not observed to be converted into shale. On the eastern face of the green-stone ridge, forty rods north of (C), on the west bank of the brook, is (D) the lead-mine. This was first opened during the revolutionary war, and again about fifteen years ago. Several of the old pits and heaps of rubbish remain; the veins are found in a north by east direction; the minerals I have found in the rubbish are galena, in small cubical crystals, foliated, and finely granular; the crystals which are exposed to the air are often covered with a thin pulverulent coat, or they are beautifully iridescent. Blende yellow and black, the latter rare; it is in much larger masses than the galena. Pyrites; this is the rarest of the three sulphurets; the gangue is sulphate of barytes, resembling that of the former vein—often resembling coxcomb spar. Carbonate of lime; colourless and crystallized, or foliated; agatized, i.e. in layers of different colours and textures, foliated, granular, and fibrous. The fibrous layers are generally external, thin, with the fibres perpendicular to the direction of the layers. Quartz in geodes and crystallized plates, (a fine-grained green mineral, resembling disintegrated green-stone (*). On the eastern face of the green-stone ridge, between (C) and (D,) the rock is speckled with minute cavities, occupied by chalcedonies, agates, and quartz crystals. The valley of the brook is there filled with pebbles, in which I have found blue and white agates, and abundance of quartz crystals; some nearly perfect, one an inch long, with the prism and two pyramids, and some slightly tinged with amethyst.


Shepard's classic 1837 report gives this brief account:

Kensington parish in Berlin has another of these old lead-diggings. The veins containing the galena, blende [sphalerite], &c. (581) are at the junction of a ridge of trap with indurated shale. It was explored during and prior to, the revolutionary war. Unsuccessful attempts to find a body of ore were also made about thirty years ago.

Regions containing this locality

North America PlateTectonic Plate

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Standard Detailed Strunz Dana Chemical Elements

Commodity List

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


Mineral List


8 valid minerals.

List of minerals arranged by Strunz 10th Edition classification

Group 2 - Sulphides and Sulfosalts
Galena2.CD.10PbS
Pyrite2.EB.05aFeS2
Sphalerite2.CB.05aZnS
Group 4 - Oxides and Hydroxides
Quartz4.DA.05SiO2
var: Agate4.DA.05SiO2
var: Amethyst4.DA.05SiO2
var: Chalcedony4.DA.05SiO2
Group 5 - Nitrates and Carbonates
Calcite5.AB.05CaCO3
Dolomite5.AB.10CaMg(CO3)2
Group 7 - Sulphates, Chromates, Molybdates and Tungstates
Baryte7.AD.35BaSO4
Group 9 - Silicates
Prehnite9.DP.20Ca2Al2Si3O10(OH)2
Unclassified Minerals, Rocks, etc.
'Bitumen'-
'Pumpellyite'-

List of minerals arranged by Dana 8th Edition classification

Group 2 - SULFIDES
AmXp, with m:p = 1:1
Galena2.8.1.1PbS
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
AB(XO3)2
Dolomite14.2.1.1CaMg(CO3)2
Group 28 - ANHYDROUS ACID AND NORMAL SULFATES
AXO4
Baryte28.3.1.1BaSO4
Group 72 - PHYLLOSILICATES Two-Dimensional Infinite Sheets with Other Than Six-Membered Rings
Two-Dimensional Infinite Sheets with Other Than Six-Membered Rings with 4-membered rings
Prehnite72.1.3.1Ca2Al2Si3O10(OH)2
Group 75 - TECTOSILICATES Si Tetrahedral Frameworks
Si Tetrahedral Frameworks - SiO2 with [4] coordinated Si
Quartz75.1.3.1SiO2
Unclassified Minerals, Mixtures, etc.
'Bitumen'-
'Pumpellyite'-
Quartz
var: Agate
-SiO2
var: Amethyst-SiO2
var: Chalcedony-SiO2

List of minerals for each chemical element

HHydrogen
H PrehniteCa2Al2Si3O10(OH)2
CCarbon
C CalciteCaCO3
C DolomiteCaMg(CO3)2
OOxygen
O BaryteBaSO4
O Quartz (var: Amethyst)SiO2
O PrehniteCa2Al2Si3O10(OH)2
O QuartzSiO2
O Quartz (var: Chalcedony)SiO2
O CalciteCaCO3
O DolomiteCaMg(CO3)2
MgMagnesium
Mg DolomiteCaMg(CO3)2
AlAluminium
Al PrehniteCa2Al2Si3O10(OH)2
SiSilicon
Si Quartz (var: Amethyst)SiO2
Si PrehniteCa2Al2Si3O10(OH)2
Si QuartzSiO2
Si Quartz (var: Chalcedony)SiO2
SSulfur
S BaryteBaSO4
S SphaleriteZnS
S GalenaPbS
S PyriteFeS2
CaCalcium
Ca PrehniteCa2Al2Si3O10(OH)2
Ca CalciteCaCO3
Ca DolomiteCaMg(CO3)2
FeIron
Fe PyriteFeS2
ZnZinc
Zn SphaleriteZnS
BaBarium
Ba BaryteBaSO4
PbLead
Pb GalenaPbS

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

Early Jurassic
174.1 - 201.3 Ma



ID: 2790641
Hampden Basalt

Age: Early Jurassic (174.1 - 201.3 Ma)

Stratigraphic Name: Hampden Basalt

Description: Greenish-gray to black (weathers bright orange to brown), fine- to medium-grained, grading from basalt near contacts to fine-grained gabbro in the interior, composed of pyroxene and plagioclase with accessory opaques and locally olivine or devitrified glass.

Comments: Part of Central Lowlands; Newark Terrane - Hartford and Pomperaug Mesozoic Basins. Part of Newark Supergroup (Upper Triassic and Lower Jurassic). Part of Meriden Formation of Krynine (1950) (Lower Jurassic); CT005. 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:{basalt,gabbro}

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]

Triassic
201.3 - 251.902 Ma



ID: 3188891
Mesozoic volcanic and intrusive rocks

Age: Triassic (201.3 - 251.902 Ma)

Comments: Connecticut Valley Basin

Lithology: Mafic volcanic rocks; conglomerate,arkose,shale,arenite

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]

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)
Pease, John C., and Niles, John N. (1819), A gazeteer of the states of Connecticut and Rhode Island. William S. Marsh, Hartford, Connecticut.
Percival, James Gates. (1822), Notice of the locality of sulphate of barytes from which a specimen was analysed by Mr. G. T. Bowen; and various other mineral localities in Berlin, Conn. American Journal of Science: s. 1, 5: 42-45.
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): A Report on the Geological Survey of Connecticut. Hamlem, New Haven.
Harte, Charles Rufus. (1945), Connecticut's Minor Metals and Her Minerals. Proceedings of the Connecticut Society of Civil Engineers, 61st Annual Report.


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