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State Route 25 road cuts, Trumbull, Fairfield Co., Connecticut, USA

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Two drill rigs at the "new" Route 25 construction site.

State Route 25 road cuts, Trumbull, Fairfield Co., Connecticut, USA
Latitude & Longitude (WGS84): 41° 15' 34'' North , 73° 12' 27'' West
Latitude & Longitude (decimal): 41.2594444444, -73.2075

In the late 1970s, during the construction of the state Route 25 expressway, a low-temperature hydrothermal vein was found cross-cutting The Straits Schist about 0.75-mile north of the Daniels Farm Road overpass. This sub-vertical vein was less than a meter wide and featured quartz, sphalerite, fluorite, galena, pyrite, adularia, and greenockite as primary minerals, with secondary lead minerals (cerussite, pyromorphite, wulfenite) and possibly the native silver and acanthite formed from the weathering of the galena. The vein, which has similarities to those found at the Thomaston Dam railroad cut farther north, has long been exhausted and covered. The approximate coordinates are given below.

Another place (exact spot unrecorded) along the cuts produced massive siderite, quartz, galena and pyrite, similar to the occurrence at Mine Hill in Roxbury, Connecticut.

The titanium dioxide polymorphs were found elsewhere in schist along the extensive roadcuts.

Mineral List

22 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
The Straits Schist (Goshen Formation of Massachusetts)

Age: Paleozoic (358.9 - 443.8 Ma)

Stratigraphic Name: Goshen Formation; The Straits Schist

Description: Silvery to gray, non-rusty, coarse- to very coarse grained, generally poorly layered schist, composed of quartz, muscovite, biotite, oligoclase, garnet, and commonly with staurolite and kyanite or sillimanite; graphitic almost throughout. Distinctive sequence of metamorphic strata overlying the Collinsville Formation in the Bristol quad., is here correlated with the Straits Schist of Fritts (1963) in the Southington quad. Consists mainly of rusty-weathering, medium- to coarse-grained, commonly crenulated, garnet-bearing, graphitic, muscovite-rich, plagioclase-quartz schist with graded bedding. Unit is called The Straits Schist following the original usage of Rodgers and others (1959). In the southern part of the Bristol quad., unit includes the Southington Mountain Member (here reduced in rank) in its upper part. Age of The Straits is inferred to be Silurian or Devonian. Unit is tentatively correlated with the Goshen Formation based on lithologic similarities and a possible unconformity at the base (Simpson, 1990).

Comments: Part of Central Lowlands; Iapetus (Oceanic) Terrane - Connecticut Valley Synclinorium; Hartland Belt Secondary unit description per CT008.

Lithology: Major:{schist}

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.


Hiller, John. (1980), Greenockite in Connecticut. The Thumbnail News: August-September: 2.

Januzzi, Ronald E. (1994), Mineral Data Book - Western Connecticut and Environs. Mineralogical Press, Danbury, Connecticut.

Henderson, William A. (1995), Microminerals of Connecticut. Rocks & Minerals (Connecticut Issue): 70(6): 420-421.

Weber, Marcelle H. and Earle C. Sullivan. (1995), Connecticut Mineral Locality Index. Rocks & Minerals (Connecticut Issue): 70(6): 397.

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