|Latitude & Longitude (WGS84):||41° 16' 4'' North , 73° 26' 21'' West|
|Latitude & Longitude (decimal):||41.26778,-73.43917|
|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):
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:
The quarry and underground workings have been inactive since 1944 and most of it is flooded.
Cameron et al (1954) state that:
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 ListThis is a list of exploitable or exploited mineral commodities recorded at this locality.
69 valid minerals. 9 (TL) - type locality of valid minerals. 8 erroneous literature entries.
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
|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.
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. 
|Ordovician - Neoproterozoic|
443.8 - 1000 Ma
|Precambrian-Phanerozoic sedimentary rocks|
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.