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Fillow Quarry (Branchville Quarry; Branchville Mica Mine; Smith Mine), Branchville, Redding (Reading), Fairfield Co., Connecticut, USA

This page kindly sponsored by Stamford Mineralogical Society
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Latitude & Longitude (WGS84): 41° 16' 4'' North , 73° 26' 21'' West
Latitude & Longitude (decimal): 41.26778,-73.43917
GeoHash:G#: dr7fbbe4p
Locality type:Quarry
Köppen climate type:Cfa : Humid subtropical climate

A lithium-rich granite pegmatite most famous for its manganese phosphates (Brush and Dana (1878, 1879, 1890)) and alteration of spodumene (Brush and Dana (1880)), which occurs in scattered crystals in a matrix of cleavelandite. About 40 percent of the spodumene is unaltered; the remainder is altered in various degrees - by very fine-grained, parallel fibers of albite and eucryptite or by further alteration to “cymatolite” - fine-grained, parallel fibers of albite and muscovite. Extreme alteration resulted in replacement by yellow, fine-granular microcline or greasy, greenish "killinite" or "pinite". Individual crystals may show in cross-section a continuum of these states of alterations.

The manganese phosphates, of which lithiophilite is the most common, occur in rare, scattered concentrations within the cleavelandite-spodumene unit. There are two kinds of concentrations: (1) those in which lithiophilite and manganapatite are the sole manganese phosphates, and (2) those in which three or more phosphate minerals are present. Yellowish-brown lithiophilite occurs in isolated ellipsoidal nodules ranging from ¼ inch to more than 1 foot in length. The nodules are invariably coated with bluish-black manganese oxide.

The discoverer of the new minerals is controversial, but research by Januzzi (1997) indicates that original quarrier Abijah Fillow set some of the unusual minerals aside in 1876-7. In the late summer of 1877, James D. Dana took some of them back to Yale. The following year George J. Brush announced the discovery of a new mineral that the Reverend (and mineralogist) John Dickinson had found at the quarry in 1877. Following this, Brush and Edward S. Dana worked the quarry with Fillow for specimens of new minerals, and Dickinson donated additional specimens from his first visits in 1877. Clearly, both Dickinson and Fillow deserve credit and were given so with new mineral names.

According to Cameron et al (1954):

The property is owned by David Schornick of Branchville. The first excavation was made in 1876 by A. Fillow of Branchville, who quarried the pegmatite for mica, abandoning it before 1878. G. B. Brush and E. S. Dana, of Yale University, mined the pegmatite in 1878 and 1879 with funds furnished by Yale. The Union Porcelain Works of Greenpoint, N. Y., bought the property in 1880 and operated it for feldspar and quartz until at least 1890. The Bridgeport Wood Finishing Co. is reported to have operated it for quartz and feldspar prior to 1920. Fred and Joseph Burrough and Carlo Rusconi, all of North Branford, operated the mine for mica from September 1943 to November 1944. The Sandy Ridge Mica & Mining Co., 927 15th Street NW., Washington, D. C., worked the mine in November and December 1944.

Januzzi (1997) reports that when the Union Porcelain Works operated the quarry in 1880-90 it was known as the Smith Mine. During that time three to four thousand tons of feldspar and four thousand tons of quartz were shipped.

Elwell (1937) reported that in 1934:

a few blasts [were] put in for sample purposes. Operations lasted only three weeks; the men were not paid and then all activities ceased; the quarry is once more filled with water and abandoned.

The quarry and underground workings have been inactive since 1944 and most of it is flooded.

Cameron et al (1954) state that:

The main working (pl. 42) is an opencut 240 feet long, 50 to 85 feet wide and 60 feet in maximum depth. A crosscut 20 feet long has been driven into the north wall of the cut, and from this one drift extends 75 feet northwest and another 57 feet southeast. Both open cut and drifts are partly backfilled. About 2,300 tons of rock was moved between September 1943 and December 1944.

The pegmatite is composed chiefly of quartz and cleavelandite with subordinate muscovite. It has a striking internal structure. The following units are found successively inward from the wall: quartz-oligoclase zone, muscovite-quartz zone, cleavelandite-quartz unit, cleavelandite unit, cleavelandite-spodumene unit and quartz core.

Another detailed description of the pegmatite's structure is given by Shainin (1946).

In the late 1970s, an attempt was made to open the site to educational mineral collecting (as opposed to a mine or quarry). The town government decided such an operation should be regulated like a school, placing so many obstacles on what should have been a very simple program that the attempt was abandoned.

Note that the quarry is located in the Town of Redding, but that the village of Branchville, situated immediately southwest of the quarry, is actually in the neighboring Town of Ridgefield. Because of the long history of the use of "Branchville" as a place name for this locality, it is included in the hierarchy.

Commodity List

This is a list of exploitable or exploited mineral commodities recorded at this locality.

Mineral List


var: Cleavelandite

var: Oligoclase

Alluaudite ?








var: Aquamarine

var: Goshenite

var: Heliodor

var: Morganite



Brazilianite ?






Dickinsonite-(KMnNa) (TL)


Eosphorite (TL)

Eucryptite (TL)

Fairfieldite (TL)

Fillowite (TL)


var: Mn-bearing Fluorapatite


var: Chlorophane

'Garnet Group'



'Gummite' ?








Landesite ?

Lazulite ?


Lithiophilite (TL)


'Manganese Oxides'

'var: Manganese Dendrites'






Microlite Group





var: Damourite

Natrophilite (TL)


var: Opal-AN





Pyromorphite ?


var: Rose Quartz

var: Smoky Quartz

Reddingite (TL)




Sicklerite ?

Spessartine ?



var: Kunzite

Staurolite ?










Triploidite (TL)






Xanthoxenite ?


var: Cyrtolite

69 valid minerals. 9 (TL) - type locality of valid minerals. 8 erroneous literature entries.

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

Eifelian - Lochkovian
387.7 - 419.2 Ma

ID: 2896343
Ordovician? granitic gneiss

Age: Devonian (387.7 - 419.2 Ma)

Description: (Including local terms Ansonia, Mine Hill, "Tyler Lake," "Siscowit") - White, light-gray, buff, or pink, generally foliated granitic gneiss, composed of sodic plagioclase, quartz, microcline, muscovite, and biotite, and locally garnet or sillimanite. Commonly contains numerous inclusions or layers of mica schist and gneiss.

Comments: Part of Central Lowlands; Iapetus (Oceanic) Terrane - Connecticut Valley Synclinorium; Ansonia Gneiss is here referred to as Ansonia leucogranite. On the basis of field and laboratory studies, Ansonia, Beardsley, Pumpkin Ground, and Shelton gneisses, previously considered stratigraphic units, are reinterpreted as plutonic. Ansonia is described as a strongly lineated and moderately foliated, fine-grained, garnet-bearing, biotite-muscovite leucogranite with a well-developed granoblastic texture. Intrudes Beardsley and Pumpkin Ground orthogneisses. Maximum age from zircons is 417+/-1.5 Ma. Conservative interpretation of isotopic data is crystallization between 393 and 419 Ma and therefore, authors assign an age of 406+/-13 Ma (Late Silurian to Early Devonian) to the Ansonia (Sevigny and Hanson, 1993) per CT007.

Lithology: Major:{gneiss}, Minor:{mica 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]

Ordovician - Neoproterozoic
443.8 - 1000 Ma

ID: 3190671
Precambrian-Phanerozoic sedimentary rocks

Age: Neoproterozoic to Ordovician (443.8 - 1000 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

This page contains all mineral locality references listed on mindat.org. 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 mindat.org 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.


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Brush, George J. and Edward S. Dana (1878) Notice of three new Phosphates from Fairfield County, Connecticut. American Journal of Science: s. 3, 15: 398-399.
Brush, George J. and Edward S. Dana (1878) Notice of a fourth new Phosphate from Fairfield Co., Connecticut. American Journal of Science: s. 3, 15: 481-2.
Brush, George J. and Edward S. Dana (1878) On a new and remarkable mineral locality in Fairfield County, Connecticut; with a description of several new species occurring there. First Paper. American Journal of Science: s. 3, 16: 33-46, 114-123.
Brush, George J. and Edward S. Dana (1879) On the Mineral Locality in Fairfield County, Connecticut, with the description of two additional new species. Second Paper. American Journal of Science: s. 3, 17: 359-368.
Brush, George J. and Edward S. Dana (1879) On the Mineral Locality in Fairfield County, Connecticut. Third Paper. American Journal of Science: s. 3, 18: 45-50.
Penfield, Samuel L. (1879) On the Chemical Composition of Amblygonite. American Journal of Science: s.3, 18: 295-301.
Comstock, W. J. (1880) Analyses of Some American Tantalates. American Journal of Science: s. 3, 19: 131-2.
Comstock, W. J. (1880) On the chemical composition of the uraninite from Branchville, Connecticut. American Journal of Science: s. 3, 19: 220-222.
Penfield, Samuel L. (1880) Analyses of some Apatites containing Manganese. American Journal of Science: s.3, 19: 367-369.
Brush, George J. and Edward S. Dana. (1880) On the Mineral Locality at Branchville, Connecticut: Fourth Paper. Spodumene and the results of its Alteration. American Journal of Science: s. 3, 20: 257-285.
Penfield, Samuel L. (1883) Analyses of two varieties of lithiophilite (manganese triphylite). American Journal of Science: s. 3, 26: 176.
Brush, George J., Edward S. Dana, and Horace L. Wells (1890) On the Mineral Locality at Branchville, Connecticut: Fifth Paper; With analyses of several manganese phosphates. American Journal of Science: s. 3, 39: 210-216.
Hillebrand, W. F. (1890) On the occurrence of nitrogen in uraninite and on the composition of uraninite in general. American Journal of Science. s. 3, 40: 384-394.
Boltwood, B. B. (1907) On the ultimate disintegration products of the radioactive elements. American Journal of Science: s. 4, 23: 78-88.
Schairer, John F. (1931) Minerals of Connecticut. State Geological and Natural History Survey of Connecticut Bulletin 51.
Elwell, Wilbur. (1937) Some Old Localities in Connecticut. Rocks and Minerals: 12(9): 270-1.
Cameron, E N., Larrabee, D. M., McNair, A. H., Page, J. J., Shainin, V E., and Stewart, G. W. (1945) Structural and economic characteristics of New England mica deposits. Economic Geology: 40: 369-393.
Shainin, V. (1946) The Branchville, Connecticut, Pegmatite. American Mineralogist: 31: 329-345.
Palache, C., Berman, H., & Frondel, C. (1951) The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II: 851, 876, 938.
Sohon, Julian A. (1951) Connecticut Minerals. State Geological and Natural History Survey of Connecticut Bulletin 77.
Cameron, Eugene N., Larrabee David M., McNair, Andrew H., Page, James T., Stewart, Glenn W., and Shainin, Vincent E. (1954) Pegmatite Investigations 1942-45 New England; USGS Professional Paper 255.
Neues Jahrbuch für Mineralogie, Monatshefte (1957): 78.
Januzzi, Ronald E. (1959) The Minerals of Western Connecticut and Southeastern New York. Mineralogical Press, Danbury, Connecticut.
Jones, Robert W. Jr., (1960) Luminescent Minerals of Connecticut, A Guide to Their Properties and Locations. Fluorescent House. Branford, Connecticut.
Schooner, Richard. (1961) The Mineralogy of Connecticut. Fluorescent House, Branford, Connecticut.
Henderson, William A., Jr. (1975) The Bertrandites of Connecticut. Mineralogical Record: 6(3): 114-123.
errors listed in Januzzi and Seaman (1976) Mineral Localities of Connecticut and Southeastern New York State and Pegmatite Minerals of the World. Mineralogical Press, Danbury, Connecticut.
Ryerson, Kathleen H. (1976) Rock Hound’s Guide to Connecticut. Pequot Press.
Marcin, Edward J. (1981) Branchville, Fairfield County, Connecticut: A Classic Mineral Locality. Rocks and Minerals: 56: 67-69.
Lapis (1984): 2: 5.
Zanazzi et al. (1986) Dehydration from switzerite. American Mineralogist 71: 1224-1228.
minerals listed in error in Tschernich, R. (1992) Zeolites of the World. Geoscience Press, Phoenix: 114.
Januzzi, Ronald. E. (1994) Mineral Data Book - Western Connecticut and Environs. Mineralogical Press, Danbury, Connecticut.
Weber, Marcelle H. and Earle C. Sullivan (1995) Connecticut Mineral Locality Index. Rocks & Minerals (Connecticut Issue): 70(6) (November/December): 396.
Januzzi, Ronald E. (1997) The Branchville Quarry and the Dickinson/Fillow Controversy. Mineralogical Press, Danbury, Connecticut.
Vajdak, Josef (1999) New Mineral Finds in the First Half of 1999. Mineral News: 15(7): 2, 4.
Vajdak, Josef (2000) New Mineral Finds in the Second Half of 2000. Mineral News: 17(1): 1, 4, 5.

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