|Latitude & Longitude (WGS84):||41° 27' 20'' North , 71° 56' 41'' West|
|Latitude & Longitude (decimal):||41.45556,-71.94472|
|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 TypeStandard Detailed Strunz Dana Chemical Elements
Detailed Mineral List:
| ⓘ Kaolinite|
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|
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.
Habit: stubby prisms, some with "corncob" habit, commonly in parallel-growth, doubly-terminated plates
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|
|Group 8 - Phosphates, Arsenates and Vanadates|
|Group 9 - Silicates|
List of minerals arranged by Dana 8th Edition classification
|Group 42 - HYDRATED PHOSPHATES, ETC.CONTAINING HYDROXYL OR HALOGEN|
|Group 75 - TECTOSILICATES Si Tetrahedral Frameworks|
|Si Tetrahedral Frameworks - SiO2 with  coordinated Si|
|Unclassified Minerals, Rocks, etc.|
List of minerals for each chemical element
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
145 - 201.3 Ma
|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
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. 
|Devonian - Silurian|
358.9 - 443.8 Ma
|Paleozoic sedimentary and volcanic rocks|
Age: Paleozoic (358.9 - 443.8 Ma)
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.