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Eureka Quarry, East Hampton (Chatham), Middlesex Co., Connecticut, USAi
Regional Level Types
Eureka QuarryQuarry
East Hampton (Chatham)- not defined -
Middlesex Co.County
ConnecticutState
USACountry

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Latitude & Longitude (WGS84):
41° 31' 47'' North , 72° 31' 58'' West
Latitude & Longitude (decimal):
Locality type:
Nearest Settlements:
PlacePopulationDistance
Higganum1,698 (2017)4.2km
East Hampton2,691 (2017)5.7km
Moodus1,413 (2017)7.5km
Lake Pocotopaug3,436 (2017)7.9km
Portland5,862 (2017)10.2km


This obscure, short-lived locality on the pegmatite ridge above the Selden cemetery, apparently had some interesting but very localized mineralogy, including pocket elbaite and lepidolite similar to the Gillette Quarry a couple of miles south of it, as described below by Bastin (1910):

Eureka Mining and Operating Company’s quarry. A small quarry operated by this company is located about 1 1/2 miles southeast of Middle Haddam. The quarry had been worked only a short time when the writer visited it, in November, 1907. It consisted of a single pit on a northeast hillside. The breast opened here is about 50 feet high and 40 feet wide. The rock is a typical granite pegmatite. Quartz does not occur in masses large enough to be commercially valuable. The feldspar is cream-colored orthoclase and microcline, finely intergrown with small amounts of albite. It seldom occurs in pure masses more than 2 feet across, the commercial product being principally graphic granite.

Muscovite occurs in “books,” most of them 4 to 5 inches, but some of them 8 inches across, and shows wedge structure and ruling, none of it being of commercial grade except for grinding. It also occurs in flat intergrowths with quartz, some of which are one-fourth inch to one-half inch thick and 2 feet across.

Biotite [annite] occurs in crystals, some of them 3 to 4 inches across, and is frequently inclosed by muscovite in parallel intergrowth. Black tourmaline is also moderately abundant, the largest crystal observed being 3 inches in diameter. Some is in graphic intergrowth with quartz.

Pockets or cavities are irregularly distributed through this pegmatite. The largest are 7 or 8 inches in diameter, and some of them, especially the smaller ones, contain tourmalines of gem quality. In color these are usually grass to olive green, and many show very perfect terminations. Some are of the variety achroite, being colorless or very pale green or pink. Near the pockets opaque or translucent green tourmalines, granular aggregates of lepidolite, and muscovite bordered by lepidolite or in parallel intergrowth with it, are common. The gem tourmalines are, as a rule, found lying in sand-like matrices at the bottoms of the pockets.

The rocks bordering this pegmatite are mica schists, probably the Bolton schist of the Connecticut Geological Survey, which strikes N. 25° W. The pegmatite, which constitutes practically the whole of the ridge in which the quarry is located, appears to be a dikelike mass whose greatest length is about parallel to the trend of the schist. The natural exposures on the summit of this ridge and on the western slope show considerable amounts of feldspar of pottery grade, some pure feldspar crystals being 3 feet across.
The width of the ridge appears to be about 150 feet. Quarrying is done in the usual manner, and the spar is hauled by teams about 1 1/4 miles to Connecticut River, where it is shipped to Trenton, N. J., in barges.


Shannon (1920) visited it and was not impressed:

About 1 1/2 kilometers (two miles) north of the [Swanson] lepidolite mine is an old quarry which, according to Bastin has yielded achroite tourmalines, etc. It is located on a low knob just south of an east-west road. It is abandoned, and shows now no sign of tourmaline-bearing pockets, or of cleavelandite, lepidolite or other interesting minerals. The quarry face shows normal granite-pegmatite too rich in biotite [annite] and black tourmaline to be of economic value. Some small rose-red garnets and specimens of biotite and muscovite in parallel position were the only things brought away from this quarry, which is scarce worth a visit.

Regions containing this locality

North America PlateTectonic Plate

Select Mineral List Type

Standard Detailed Strunz Dana Chemical Elements

Mineral List


7 valid minerals.

Detailed Mineral List:

Albite
Formula: Na(AlSi3O8)
Description: Pegmatite matrix.
Reference: Baston, Edson S. (1910), Economic Geology of the Feldspar Deposits of the United States. United States Geological Survey Bulletin 420.
Annite
Formula: KFe2+3(AlSi3O10)(OH)2
Colour: black
Description: Crystals to 3 to 4 inches across, commonly enclosed by muscovite in parallel intergrowth.
Reference: Baston, Edson S. (1910), Economic Geology of the Feldspar Deposits of the United States. United States Geological Survey Bulletin 420.
Elbaite
Formula: Na(Li1.5Al1.5)Al6(Si6O18)(BO3)3(OH)3(OH)
Colour: grass to olive green, colorless or very pale green or pink
Description: Opaque to gem quality, found in the muck at the bottom of pockets or cavities up to 7 or 8 inches in diameter. Near the pockets opaque or translucent green tourmalines are common.
Reference: Baston, Edson S. (1910), Economic Geology of the Feldspar Deposits of the United States. United States Geological Survey Bulletin 420.
'Garnet Group'
Formula: X3Z2(SiO4)3
Colour: rose-red
Description: Crystals reportedly small.
Reference: Shannon, Earl V. (1920), The Old Lithia Mine in Chatham, Connecticut. American Mineralogist: 5: 82-84.
'Lepidolite'
Description: Near the pockets opaque or translucent green tourmalines, granular aggregates of lepidolite, and muscovite bordered by lepidolite or in parallel intergrowth with it, are common.
Reference: Baston, Edson S. (1910), Economic Geology of the Feldspar Deposits of the United States. United States Geological Survey Bulletin 420.
Microcline
Formula: K(AlSi3O8)
Colour: cream
Description: Mostly as graphic granite intergrowths with quartz to 2 feet across.
Reference: Baston, Edson S. (1910), Economic Geology of the Feldspar Deposits of the United States. United States Geological Survey Bulletin 420.
Muscovite
Formula: KAl2(AlSi3O10)(OH)2
Description: Muscovite occurs in “books,” most of them 4 to 5 inches, but some of them 8 inches across, and shows wedge structure and ruling, none of it being of commercial grade except for grinding. It also occurs in flat intergrowths with quartz, some of which are one-fourth inch to one-half inch thick and 2 feet across. Also parallel intergrowths with annite. Near the pockets opaque or translucent green tourmalines, granular aggregates of lepidolite, and muscovite bordered by lepidolite or in parallel intergrowth with it, are common.
Reference: Baston, Edson S. (1910), Economic Geology of the Feldspar Deposits of the United States. United States Geological Survey Bulletin 420.
Quartz
Formula: SiO2
Description: Pegmatite matrix.
Reference: Baston, Edson S. (1910) Economic Geology of the Feldspar Deposits of the United States. United States Geological Survey Bulletin 420.
Schorl
Formula: Na(Fe2+3)Al6(Si6O18)(BO3)3(OH)3(OH)
Description: Black tourmaline is also moderately abundant, the largest crystal observed being 3 inches in diameter. Some is in graphic intergrowth with quartz.
Reference: Baston, Edson S. (1910), Economic Geology of the Feldspar Deposits of the United States. United States Geological Survey Bulletin 420.

List of minerals arranged by Strunz 10th Edition classification

Group 4 - Oxides and Hydroxides
Quartz4.DA.05SiO2
Group 9 - Silicates
Albite9.FA.35Na(AlSi3O8)
Annite9.EC.20KFe2+3(AlSi3O10)(OH)2
Elbaite9.CK.05Na(Li1.5Al1.5)Al6(Si6O18)(BO3)3(OH)3(OH)
Microcline9.FA.30K(AlSi3O8)
Muscovite9.EC.15KAl2(AlSi3O10)(OH)2
Schorl9.CK.05Na(Fe2+3)Al6(Si6O18)(BO3)3(OH)3(OH)
Unclassified Minerals, Rocks, etc.
'Garnet Group'-X3Z2(SiO4)3
'Lepidolite'-

List of minerals arranged by Dana 8th Edition classification

Group 61 - CYCLOSILICATES Six-Membered Rings
Six-Membered Rings with borate groups
Elbaite61.3.1.8Na(Li1.5Al1.5)Al6(Si6O18)(BO3)3(OH)3(OH)
Schorl61.3.1.10Na(Fe2+3)Al6(Si6O18)(BO3)3(OH)3(OH)
Group 71 - PHYLLOSILICATES Sheets of Six-Membered Rings
Sheets of 6-membered rings with 2:1 layers
Annite71.2.2b.3KFe2+3(AlSi3O10)(OH)2
Muscovite71.2.2a.1KAl2(AlSi3O10)(OH)2
Group 75 - TECTOSILICATES Si Tetrahedral Frameworks
Si Tetrahedral Frameworks - SiO2 with [4] coordinated Si
Quartz75.1.3.1SiO2
Group 76 - TECTOSILICATES Al-Si Framework
Al-Si Framework with Al-Si frameworks
Albite76.1.3.1Na(AlSi3O8)
Microcline76.1.1.5K(AlSi3O8)
Unclassified Minerals, Mixtures, etc.
'Garnet Group'-X3Z2(SiO4)3
'Lepidolite'-

List of minerals for each chemical element

HHydrogen
H ElbaiteNa(Li1.5Al1.5)Al6(Si6O18)(BO3)3(OH)3(OH)
H AnniteKFe32+(AlSi3O10)(OH)2
H SchorlNa(Fe32+)Al6(Si6O18)(BO3)3(OH)3(OH)
H MuscoviteKAl2(AlSi3O10)(OH)2
LiLithium
Li ElbaiteNa(Li1.5Al1.5)Al6(Si6O18)(BO3)3(OH)3(OH)
BBoron
B ElbaiteNa(Li1.5Al1.5)Al6(Si6O18)(BO3)3(OH)3(OH)
B SchorlNa(Fe32+)Al6(Si6O18)(BO3)3(OH)3(OH)
OOxygen
O ElbaiteNa(Li1.5Al1.5)Al6(Si6O18)(BO3)3(OH)3(OH)
O AnniteKFe32+(AlSi3O10)(OH)2
O SchorlNa(Fe32+)Al6(Si6O18)(BO3)3(OH)3(OH)
O Garnet GroupX3Z2(SiO4)3
O MuscoviteKAl2(AlSi3O10)(OH)2
O AlbiteNa(AlSi3O8)
O MicroclineK(AlSi3O8)
O QuartzSiO2
NaSodium
Na ElbaiteNa(Li1.5Al1.5)Al6(Si6O18)(BO3)3(OH)3(OH)
Na SchorlNa(Fe32+)Al6(Si6O18)(BO3)3(OH)3(OH)
Na AlbiteNa(AlSi3O8)
AlAluminium
Al ElbaiteNa(Li1.5Al1.5)Al6(Si6O18)(BO3)3(OH)3(OH)
Al AnniteKFe32+(AlSi3O10)(OH)2
Al SchorlNa(Fe32+)Al6(Si6O18)(BO3)3(OH)3(OH)
Al MuscoviteKAl2(AlSi3O10)(OH)2
Al AlbiteNa(AlSi3O8)
Al MicroclineK(AlSi3O8)
SiSilicon
Si ElbaiteNa(Li1.5Al1.5)Al6(Si6O18)(BO3)3(OH)3(OH)
Si AnniteKFe32+(AlSi3O10)(OH)2
Si SchorlNa(Fe32+)Al6(Si6O18)(BO3)3(OH)3(OH)
Si Garnet GroupX3Z2(SiO4)3
Si MuscoviteKAl2(AlSi3O10)(OH)2
Si AlbiteNa(AlSi3O8)
Si MicroclineK(AlSi3O8)
Si QuartzSiO2
KPotassium
K AnniteKFe32+(AlSi3O10)(OH)2
K MuscoviteKAl2(AlSi3O10)(OH)2
K MicroclineK(AlSi3O8)
FeIron
Fe AnniteKFe32+(AlSi3O10)(OH)2
Fe SchorlNa(Fe32+)Al6(Si6O18)(BO3)3(OH)3(OH)

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

Devonian - Silurian
358.9 - 443.8 Ma



ID: 3186140
Paleozoic sedimentary and volcanic rocks

Age: Paleozoic (358.9 - 443.8 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]

Late Ordovician - Middle Ordovician
443.8 - 470 Ma



ID: 2978277
Collins Hill Formation

Age: Ordovician (443.8 - 470 Ma)

Stratigraphic Name: Collins Hill Formation

Description: ( = Partridge Formation of New Hampshire) - Gray, rusty-weathering, medium- to coarse-grained, poorly layered schist, composed of quartz, oligoclase, muscovite, biotite, and garnet, and commonly staurolite, kyanite, or sillimanite, generally graphitic, interlayered with fine-grained two-mica gneiss, especially to the west, and with calc-silicate and amphibolite layers, also rare quartz-spessartine (coticule) layers.

Comments: Part of Eastern Uplands; Iapetus (Oceanic) Terrane - Bronson Hill Anticlinorium; Brimfield Schist and equivalent formations (includes Collins Hill Formation) (Upper? and Middle Ordovician). 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:{schist}, Minor:{gneiss}, Incidental:{amphibolite, calc silicate rock}

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)
Baston, Edson S. (1910) Economic Geology of the Feldspar Deposits of the United States. United States Geological Survey Bulletin 420.
Shannon, Earl V. (1920), The Old Lithia Mine in Chatham, Connecticut. American Mineralogist: 5: 82-84.


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