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Becker Quarry (Becker's Quarry), West Willington, Willington, Tolland Co., Connecticut, USA

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Latitude & Longitude (WGS84): 41° 52' 19'' North , 72° 16' 24'' West
Latitude & Longitude (decimal): 41.87222,-72.27361
Köppen climate type:Dfb : Warm-summer humid continental climate

Most famous for its Tessin habit and sceptered quartz crystals, plus assemblage of magnesite, almandine, pyrite, tourmaline, and free-standing kyanite crystals. As described by Ague (1995), the host rock is a granulite facies mafic gneiss (metagabbro) consisting of anorthite (An70-80), clinopyroxene, orthopyroxene and biotite with accessory quartz, and retrograde magnesio-hornblende and cummingtonite. Hydrothermal vein minerals formed in open Alpine-type fractures that cross-cut the foliation of the bedrock when it was under amphibolite facies conditions - about 15-30 km deep and 500-550 degrees C. The most common assemblage is quartz-almandine-kyanite-magnesite-biotite-albite (An20-40)-ankerite-muscovite. Less common is quartz-almandine-magnesio-hornblende-magnesite-albite (An20-40)-ankerite-biotite. Also in the veins are accessory staurolite, fluorapatite, tourmaline, zircon, ilmenite, pyrrhotite and chalcopyrite crystals (and rutile not mentioned by Ague). Calcite and pyrite formed under lower P-T conditions much later. Many minerals are coated with a dull gray-green layer of very fine-grained, retrograde sericite/chlorite/clay.

This is an operating quarry and collecting is not allowed without permission, which in recent years is rarely given.

Mineral List

21 valid minerals.

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

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]

Ordovician - Cambrian
443.8 - 541 Ma

ID: 2820363
Gneiss (metavolcanic) member [of Brimfield Schist]

Age: Paleozoic (443.8 - 541 Ma)

Stratigraphic Name: Brimfield Schist

Description: Medium-gray, medium-grained, layered gneiss and schist, composed of oligoclase, quartz, and biotite; some gneiss and most schist layers contain garnet and sillimanite; some gneiss layers contain garnet, hornblende or pyroxene or grade into amphibolite or calc-silicate rock. Probably includes metavolcanic rocks.

Comments: Part of Eastern Uplands; Iapetus (Oceanic) Terrane - Merrimack Synclinorium; Brimfield Schist and equivalent formations (includes Tatnic Hill Formation) (Upper? and Middle Ordovician). The age of the Brimfield Group in this area is Cambrian(?) based on the intrusion of 440 my Hedgehog Hill gneiss in the top of the Hamilton Reservoir Formation in the upper part of the Brimfield, although the top of the Brimfield may be Ordovician or older Paleozoic (Pease, 1989) per CT013.

Lithology: Major:{gneiss,schist}, Incidental:{amphibolite, calc silicate rock, metavolcanic}

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, used under Creative Commons Attribution 4.0 License

This page contains all mineral locality references listed on This does not claim to be a complete list. If you know of more minerals from this site, please register so you can add to our database. This locality information is for reference purposes only. You should never attempt to visit any sites listed in without first ensuring that you have the permission of the land and/or mineral rights holders for access and that you are aware of all safety precautions necessary.


Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Scovil, J. (1994), What's New in Minerals. Mineralogical Record: 25: 377.
Zagielski, M., and J. Fast. (1994), A new occurrence of almandine, kyanite, and quartz in open veins in Willington, Connecticut (abstract). Rocks & Minerals 69: 136.
Ague, J. J. (1995), Deep Crustal Growth of Quartz, Kyanite and Garnet into Large-Aperature, fluid-filled fractures, northeastern Connecticut, USA. Journal of Metamorphic Geology: 13: 299-314.
Weber, Marcelle H. and Earle C. Sullivan. (1995), Connecticut Mineral Locality Index. Rocks & Minerals (Connecticut Issue): 70(6): 407.
Horowitz, Irving L. (2003), The Remarkable Quartz Crystals of West Willington, Tolland County, Connecticut. Rocks & Minerals: 78(4): 257-261.

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