Danburite type locality, Danbury, Fairfield Co., Connecticut, USA
|Latitude & Longitude (WGS84):||41° 23' 45'' North , 73° 27' 15'' West|
|Latitude & Longitude (decimal):||41.39611,-73.45417|
|Köppen climate type:||Cfa : Humid subtropical climate|
Shepard (1839) gives a brief (and the only) description of the type locality of danburite:
The mineral, believed to be new, is observed disseminated in small amounts or quantities throughout the feldspar (with which is likewise associated a small quantity of quartz) in fissures and cavities having the shape apparently of oblique prisms. Owing to the partial decomposition of the mineral (a change to which it appears particularly liable) these cavities are sometimes entirely empty. The largest of them noted was above one inch in one direction by one-fifth of an inch in another.
Whether the mineral will be found in any considerable quantity I am unable to say. The specimens collected have been barely sufficient to afford the following notice.
Shepard reports finding the danburite in 1837. Fortunately, Dana (1850) reports that George Brush apparently obtained more material. And Brush (1858) also reports the site "was re-opened during the past year". Sadly, none of these investigators made a better description of the locality than Shepard's brief and vague initial one and the spot has become lost. Consequently, 20th-century collectors and investigators have taken up the search.
According to Januzzi (1976), a proposed site is near the intersection of North Street and Padanaram Road.
Most of the rock exposures in the vicinity of North Street and Padanaram Road where Shepard is believed to have discovered danburite has, for years, been covered by topsoil and vegetation, and such rock outcrops that are free of overburden are greatly discolored. This fact made it very difficult, if not impossible, for anyone to locate the exact environment of Shepard’s find. About two years ago considerable removal of rock began to take place at the end of North Street and the beginning of Padanaram Road for the construction of a small commercial site. The minerals that came to light during this operation leave no doubt in my mind that this was the geologic local of Shepard’s discovery.
Januzzi (1994) commented further about the type locality:
The area in question is a plutonic - marble contact situated on the western side of the intersection of Hayestown Avenue, North Street, and Padanaram Road in the city of Danbury, Connecticut. The outcrop was exposed during construction for a commercial building.
The exact site of Col. White’s Factory is the crucial clue, especially since there was more than one establishment that bore this name.
Danburite could have possibly been found at two different areas within a relatively short distance of each other (note the dissimilarities occurring in two specimens of the species, both collected in the hamlet of Danbury - see photographs No. 5 and 29, series A); the two samples might have also originated in differentially localized areas of the same petrologic environment.
Shepard might have given a preview of danburite before his official publication on the species (1839) in the American Journal of Science; this could have been accomplished by personal correspondence between Shepard and collectors, both professional and amateur, with whom he had an acquaintance in the state, particularly in the New Haven area which was one of the centers of culture in New England, with Yale College being at the hub of geologic and mineralogic exploration, led by the internationally eminent Professor James Dwight Dana.
Because of the stature of the men involved it is not beyond the parameters of reason that lines of communication were kept open, especially through mutual correspondence.
It is therefore well within the realm of possibility that others interested in the survey and with the information that Shepard could have supplied visited a number of areas in which field work had been done. Natural outcrops, from North Street on one side of town to Edgewood Street on the other, could have been examined for several miles from the center of what, at that time, (1837-1839) was a tiny hamlet. This hypothesis becomes more credible when we consider that danburite has been listed as being discovered at several sites within the city, none more distant than about two miles of the center, they include: Edgewood Street, the end of Cleveland Street, the Sugar Hollow Road in Danbury, Brookfield, and of course the supposed type locality near Col. White’s factory in the vicinity of the Hayestown Ave., North St., Padanaram Rd. epicenter! In 1837, in Danbury, the only familiar geographical landmark might have been a “road” that was called “North Avenue”; the other two “roads” did not exist, as far as is known, using their modern designation (Padanaram Road and Hayestown Avenue)...
During my investigation, over many years, it is my personal opinion that the North Street area is the site of the original find; in fact I have listed danburite as one of the minerals found in the area during my research on species collected at a construction area there; whether I am right or wrong I take full responsibility for that statement, regardless of what my critics might say. I firmly believe that danburite is part of that unique mineral assemblage even if, in the end, I am proven wrong about it being the original site. It appears that the exact type locality becomes more ambiguous with time and preoccupation with historical anomalies that have superseded scientific fact.
Was it possible that more than one danburite site was uncovered in the area based upon Shepard’s word of mouth or possible correspondence before his official announcement in the American Journal of Science, if so, it might be impossible today to pinpoint exactly which specimen came from where, especially if the paragenesis, petrologic and mineralogic assemblages replicated themselves within a radius of several miles; in this case it would become an academic question whose exact solution might actually never become manifest, especially since the ravages and elements of time have conspired against us, both on a human and environmental level; with this in mind the mystery of the location of the type locality continues to persist 157 years later!
The major problem with this proposed locality is that Januzzi does not mention actually finding or describing any danburite from there. Another problem is that in the early to mid 19th century, according to maps from the 1840s and 1856 (see links below), all the mills were located on the Still River about a mile south of Januzzi's proposed locality. Even the map from as late as 1856 does not even include areas that far north of the Still River, strongly suggesting nothing of significance there. Januzzi does not mention how he came to determine that Col. White had a factory at his proposed location when maps from that era do not even include that part of town.
Instead, the White family had many properties along the river and near White Street, near the center of town, not on Padanaram Brook a mile north. The 1840s map of Danbury shows “Col. E.M. White” at the corner of Prospect and White, and also along Main Street south of White. On the 1856 map of Danbury, "E.M. White" is shown at the corner of Main and White, on Main Street, and next to the Still River where West Street crosses it, just west of Beaver Street. All these places are within the part of the city underlain by calcite and dolomite of the Stockbridge marble, seemingly a more likely formation for the paragenesis of the type locality than the granitic Proterozoic rocks of Januzzi's proposed location. In particular, the area of the Still River just west of Beaver Street has good relief and Clarke (1958) shows strikes and dips of marble exposures there. Weber and Sullivan (1995) give the general White Street area as the likely source. Consequently, the coordinates given below are for the center of the city at the intersection of Main and White Streets, which is also central to the various White properties shown on historic maps. This is still admittedly an approximation.
Of the other localities in Danbury Januzzi reports danburite finds, they all have different geology. According to Clarke (1958), only the one on Edgewood Steet is in the same formation (Proterozoic granitic rocks) as Januzzi's proposed locality. But Clarke (1958) does not mention dolomitic rocks in any formation other than the Stockbridge (Inwood) marble and only the reported locality at the "end of Cleveland Street" is within the Stockbridge marble and not far from outcrops mapped by Clarke (1958).
The list of minerals from the type locality in the 19th century literature includes only a few mentioned by Shepard (1839) (danburite, dolomite, "feldspar", quartz) and (1851) (thorite - later claimed to be "parathorite" by Dana (1857) but that is not a valid species, titanite, and augite), and Smith and Brush (1853a) (oligoclase and "potash feldspar" later found chemically to be "orthoclase" (Brush 1858) though it could be microcline). The "fetid" feldspar is mentioned by Shepard (1837) as occurring "at Danbury near Col. White's factory". This was before he identified the danburite in these rocks. Schairer (1931) mentions that brown tourmaline was reported from the type locality, but that mineral is not mentioned in the 19th-century literature. Manchester (1931) reports it too, but only for Danbury in general.
Material from the type locality preserved at the Yale Peabody Museum (New Haven, Connecticut, USA) consists of 11 specimens (small cabinet to miniature size) and small pieces shed from them. These specimens consist mostly of white albite matrix and contain abundant danburite up to about 5 cm and so are more likely from the 1850s, a belief shared by the staff. These specimens contain the following primary assemblage (generally in decreasing order of abundance): albite (presumably the oligoclase variety reported in the literature), danburite, olivine (presumably forsterite - which is mentioned by Clarke and others to occur in the Stockbridge), fluorapatite, tremolite, dolomite, and quartz. Some secondary aragonite crust coats part of a couple of pieces. This photo is very typical of the type material at Yale: http://www.mindat.org/photo-272202.html. Nothing resembling augite, K-feldspar, thorite, titanite or tourmaline (of the habits or color in the old literature) was visible. No mica is present on them either. See the mineral info for these minerals for details.
Other minerals reported by Januzzi (1976 and 1994) near the intersection of North Street and Padanaram Road cannot be verified as from the type locality and so are covered by a Mindat page for that locality found at http://www.mindat.org/loc-213272.html.
12 valid minerals.
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
|Early Ordovician - Cambrian|
470 - 541 Ma
|Stockbridge Marble (Including Inwood Marble)|
Age: Paleozoic (470 - 541 Ma)
Stratigraphic Name: Stockbridge Marble
Description: White to gray, massive to layered marble, generally dolomitic but containing calcite marble in upper part, locally interlayered with schist or phyllite and with calcareous siltstone or sandstone.
Comments: Part of Western Uplands; Proto-North American (Continental) Terrane - Carbonate Shelf
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.