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Lantern Hill Quarry (Silex Quarry; U.S. Silica Company Quarry), North Stonington, New London Co., Connecticut, USA

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Latitude & Longitude (WGS84): 41° 27' 20'' North , 71° 56' 41'' West
Latitude & Longitude (decimal): 41.45556,-71.94472
GeoHash:G#: drkgffg2n
Locality type:Quarry
Köppen climate type:Cfb : Temperate oceanic climate


A former quartz mine, opened in 1870s, in a 1.6-km-long and 71m thick quartz lode that also underlies Lantern Hill to the north of the quarry. Since 1994, the land has been owned by the Mashantucket Pequot Tribal Nation. According to Altamura (1995), high-purity silica from here was used for glass making, foundry sand, aquarium sand, swimming pool filters, sandbox sand and architectural aggregate - such as on the concrete faces of the J. F. Kennedy presidential library near Boston. The hydrothermal quartz deposit occurred along rift faults 238 Ma (from primary muscovite, early middle Triassic), 19 Ma before sedimentation in the Triassic-Jurassic Hartford Basin began.

Small quartz crystals can be found in talus along cliffs on 120 m high Lantern Hill.

Select Mineral List Type

Standard Detailed Strunz Dana Chemical Elements

Mineral List


3 valid minerals.

Detailed Mineral List:

Kaolinite
Formula: Al2(Si2O5)(OH)4
Habit: platy hexagonal
Colour: white (commonly stained)
Description: tiny crystals in fluid inclusions in quartz were tested, but the mineral is certainly ubiquitous here from the alteration of wall rocks
Reference: Museum of Natural History, Roger Williams Park, Providence, R.I. G3326 5577; Altamura, Robert J. (1995), Tectonics, Wall-Rock Alteration and Emplacement History of the Lantern Hill Giant Quartz Lode, Avalonian Terrane, Southeastern Connecticut. Trip E in Guidebook for Fieldtrips in Eastern Connecticut and the Hartford Basin. Northeast Section Geological Society of America 30th Annual Meeting. State Geological and Natural History Survey of Connecticut Guidebook No. 7.
Plumbogummite
Formula: PbAl3(PO4)(PO3OH)(OH)6
Habit: rhombohedral
Colour: bluish-green
Description: Very microscopic crystals forming crusts on quartz.
Reference: Altamura, Robert J. (1995), Tectonics, Wall-Rock Alteration and Emplacement History of the Lantern Hill Giant Quartz Lode, Avalonian Terrane, Southeastern Connecticut. Trip E in Guidebook for Fieldtrips in Eastern Connecticut and the Hartford Basin. Northeast Section Geological Society of America 30th Annual Meeting. State Geological and Natural History Survey of Connecticut Guidebook No. 7.
Quartz
Formula: SiO2
Habit: stubby prisms, some with "corncob" habit, commonly in parallel-growth, doubly-terminated plates
Colour: white
Description: Crystals can reach 6 cm.
Reference: Weber, Marcelle H. and Earle C. Sullivan. (1995): Connecticut Mineral Locality Index. Rocks & Minerals (Connecticut Issue): 70(6): 407.

List of minerals arranged by Strunz 10th Edition classification

Group 4 - Oxides and Hydroxides
'Quartz'4.DA.05SiO2
Group 8 - Phosphates, Arsenates and Vanadates
'Plumbogummite'8.BL.10PbAl3(PO4)(PO3OH)(OH)6
Group 9 - Silicates
'Kaolinite'9.ED.05Al2(Si2O5)(OH)4

List of minerals arranged by Dana 8th Edition classification

Group 42 - HYDRATED PHOSPHATES, ETC.CONTAINING HYDROXYL OR HALOGEN
(AB)2(XO4)Zq·xH2O
Plumbogummite42.7.3.5PbAl3(PO4)(PO3OH)(OH)6
Group 75 - TECTOSILICATES Si Tetrahedral Frameworks
Si Tetrahedral Frameworks - SiO2 with [4] coordinated Si
Quartz75.1.3.1SiO2
Unclassified Minerals, Rocks, etc.
Kaolinite-Al2(Si2O5)(OH)4

List of minerals for each chemical element

HHydrogen
H KaoliniteAl2(Si2O5)(OH)4
H PlumbogummitePbAl3(PO4)(PO3OH)(OH)6
OOxygen
O KaoliniteAl2(Si2O5)(OH)4
O PlumbogummitePbAl3(PO4)(PO3OH)(OH)6
O QuartzSiO2
AlAluminium
Al KaoliniteAl2(Si2O5)(OH)4
Al PlumbogummitePbAl3(PO4)(PO3OH)(OH)6
SiSilicon
Si KaoliniteAl2(Si2O5)(OH)4
Si QuartzSiO2
PPhosphorus
P PlumbogummitePbAl3(PO4)(PO3OH)(OH)6
PbLead
Pb PlumbogummitePbAl3(PO4)(PO3OH)(OH)6

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

Jurassic
145 - 201.3 Ma



ID: 2750152
Silicified rock and mylonite along Mesozoic faults

Age: Jurassic (145 - 201.3 Ma)

Description: Close network of quartz veins and veinlets cutting each other and older rock, which is mostly replaced by very fine grained quartz. In places, incompletely replaced rock shows strongly mylonitic texture.

Comments: Part of Eastern Uplands; Fault-related rocks 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:{mylonite}

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]

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]

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)
Ryerson, Kathleen H. (1972), Rock Hound's Guide to Connecticut. Pequot Press.
Altamura, Robert J. (1995), Tectonics, Wall-Rock Alteration and Emplacement History of the Lantern Hill Giant Quartz Lode, Avalonian Terrane, Southeastern Connecticut. Trip E in Guidebook for Fieldtrips in Eastern Connecticut and the Hartford Basin. Northeast Section Geological Society of America 30th Annual Meeting. State Geological and Natural History Survey of Connecticut Guidebook No. 7.
Weber, Marcelle H. and Earle C. Sullivan. (1995): Connecticut Mineral Locality Index. Rocks & Minerals (Connecticut Issue): 70(6): 407.
Pawloski, John A. (2006), Connecticut Mining. Arcadia Publishing, Mt. Pleasant, SC.


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