Lane's Mine (Lane's Lead and Silver Mine; Elm Street), Monroe, Fairfield County, Connecticut, USAi

Regional Level Types
Lane's Mine (Lane's Lead and Silver Mine; Elm Street)	Mine
Monroe	Town
Fairfield County	County
Connecticut	State
USA	Country

One of four small mines worked by the Lane family from the early-19th century and famous for native bismuth. Surprisingly, it still exists in a small area of designated open space in the middle of a residential housing development at the intersection of Flint Ridge Road (flint being an old trade term for white massive quartz, different from the purely geologic term) and Pequonock Ridge Road. As described below, it consists of two small excavations into massive, slightly vuggy quartz and a pit exposing a glacially-polished natural surface, with no adjacent host rock exposed. All exposures are rusty from weathering, none of the sulfides or bismuth are obvious via casual observation. There are patches of muscovite visible within it, but very little else to hint at its geological character. It does not seem to be the quartz core of a pegmatite as usually other pegmatite zones are exposed, too. It bears a resemblance to Permian high-temperature hydrothermal veins in the Old Mine Twin Brooks/Beach Memorial Parks in Trumbull that typically exhibit quartz cores and muscovite wall zones and can host sulfides.

The other three mines are Lane’s Copper Mine (Fan Hill Road - also in Monroe) (http://www.mindat.org/loc-234050.html), Booth-Hurd's Bismuth Mine (http://www.mindat.org/loc-8810.html), and Lane’s Mine of Trumbull (http://www.mindat.org/loc-23342.html). The inclusion of "Elm Street" in the locality name is used only on mindat to differentiate it in the locality hierarchy from the other Lane's Mine off Fan Hill Road. Nearly all references only refer to them simply as "Lane's Mine" or "Lane's Mine in Monroe".

Sullivan (1985) reported that Ephraim Lane had interests in three properties in Monroe or Huntington. This situation has lead to much confusion over the origin of mineral specimens because up until 1826 most specimens were provided by Lane without attribution. Coffey (1974) refers to the Elm Street mine as the "Lane's lead and silver mine" and operated by Ephraim Lane.

Archibald Bruce (1814) first described minerals including native bismuth, reportedly from the Lane's mine off of Elm Street in Monroe.

Hobbs (1901) describes the Elm Street Lane's Mine:
"The mine of Mr. Lane at Monroe is opened in a wide vein of quartz, which has a northerly trend. No wall rock is here exposed. The vein is rich in marcasite, and the mineral collection of E. S. Olmstead, of Long Hill, contains also sphalerite, galena, arsenopyrite, and native bismuth, all from this locality."

Similarly, Crowley (1968) gives this description:
"The mine consists of several pits and trenches sunk into massive quartz, which bears pockets and veins of sulfides. The mineralogy is, in most respects, similar to that of Booth's bismuth mine, including the reported occurrence of native bismuth (Schairer, 1931) and the wide distribution of pyrrhotite. The mine is in the western body of Collinsville Formation not far from the western contact of the westernmost belt of The Straits Schist. However, there are no outcrops of the country rock in the immediate vicinity of the mine, nor were any lenses of schist or gneiss observed in the massive quartz. Hobbs (1901) described the quartz body as having a northerly trend, although this was not obvious in the present investigation. There appears to be a nearly horizontal layering in the quartz."

Much has been written about this locality due to the number of early 19th century mineral discoveries new to North America or to mineralogy, enhanced by its proximity to Yale University. However, the early investigators did not clearly establish or document the exact origin of specimens, leading to erroneous mineral listings in later literature and the wrong type locality for tungstite. Some of the minerals, particularly the tungsten minerals, appear to be erroneously attributed to Lane's Monroe mines because Ephraim and later his son Charles were working their mine in northern Trumbull (http://www.mindat.org/loc-23342.html), near the border with Monroe, where tungsten minerals occur in a now well known and unique deposit. The Yale investigators either did not know there were multiple mines, or did not consider the distinction noteworthy, at least initially.

Descriptions of what we now call ferberite and scheelite exactly matching the Trumbull occurrence (especially the unique pseudomorphs of ferberite after scheelite) appear in Silliman (1819a, 1819b, 1819c) and in Bowen (1822). These specimens, which were generically attributed to "Lane's Mine" "Monroe", were actually purchased from and shipped by Ephraim Lane "at a reasonable price", they were not collected by Silliman or Bowen. Silliman (1819c) states that the “immediate rock which forms the walls of the vein is said to be gneiss; (we have not seen it.)”. Consequently the tungsten specimens (and perhaps any of the other minerals attributed to "Lane's Mine") could have come from any one of Ephraim Lane's mineral properties but actually match the mineralogy of his Trumbull mine based on later work.

Silliman (1822a, 1822b) and Bowen (1822) both describe and/or analyze what we now call tungstite and note it was "disseminated through the tungstite of lime [scheelite]...in cavities and fissures in the ferruginous tungsten [ferberite] of Mr. Lane’s mine". The presence of tungstite with the unique ferberite pseudomorphs after scheelite, and unaltered scheelite, can only mean the specimens came from Lane's Mine of Trumbull. Yale University has type specimens matching this description and that are identical to samples from Trumbull.

It was not until 1826 that Hitchcock (Hitchcock and Silliman, 1826) visited the Trumbull locality and confirmed the marble/amphibolite geology and said, correctly, that the locality is “four miles south of what is usually called Lane’s mine”. In Hitchcock (1828) he notes that the newly found topaz and fluorite veins in Trumbull were “connected with the Wolfram”. He summarizes geology and mineralogy completely consistent with that of the Trumbull mine, noting the tungsten minerals are in a quartz “bed…not a vein” in contact with gneiss dipping a few degrees to the northeast. Therefore, the type locality for tungstite should be changed from Lane's Mine of Monroe (Elm Street) to Lane's Mine of Trumbull.

Professor Adolph Gurlt (1893), in his report on the Trumbull tungsten deposit, referring to the earlier reports by Silliman, Percival and Shepard, stated ...:

"On the authority of these explorers, some statements about the occurrence of wolfram minerals have been widely spread through American and European scientific literature, frequently, however, with slight inaccuracies as to the locality, which is sometimes placed in Monroe and sometimes in Trumbull parish. As a fact, the [tungsten] deposit lies in the latter; and the error may be explained by the circumstance that the owner at that time, a certain Charles [actually Ephraim] Lane had been mining in both parishes, --in Monroe for lead and bismuth, which occurred in association with magnetic iron pyrites on a quartz-lode traversing gneiss, and in Trumbull at the above-mentioned place."

Also, in 1901, W. H. Hobbs reported:

"The original openings [in Trumbull] bore the name of [Ephraim - later his son Charles] Lane’s mine of Trumbull. On account of the occurrence of native bismuth and galena on the property of a Mr. [Ephraim] Lane in the adjoining township of Monroe and the opening of pits there, much confusion has arisen and there are many references to an occurrence of wolframite in Monroe, which with little doubt, are meant for the Trumbull locality."

"The confusion which has arisen has been due largely to the propinquity of the two localities and to the fact that both mines were owned by men bearing the same surname."

The listing of native tellurium from Lane's mine of Monroe is both erroneous and also from the wrong locality. A careful reading of Silliman (1819a, 1819b, 1819c) indicates that he “obtained” tellurium from “only two pieces; from which we also extracted tungsten, so that it may possibly constitute a new mineral species.” Tellurium was “unexpectedly discovered in some of the ores of tungsten” described as “dark brown, almost black; brittle” and “octahedral” crystals that clearly match the ferberite after scheelite found abundantly and uniquely at Trumbull. "Even in well defined crystals, both metals have been found in the same crystal, and where the external appearance is homogeneous. In other specimens a difference seems to be apparent, and a proper ore of tellurium appears to be blended with the proper ore of tungsten. This latter ore is wolfram, composed of oxide of tungsten, or as some choose to say, tungstic acid combined with iron and manganese. The crystals, however, are octahedral, a fact we believe is not mentioned of this species by authors, although this form is found in the calcareous tungsten." His description of the “Chemical Trials” concludes that “the ore is very similar to the ferruginous tungsten or wolfram.” Quite obviously the tellurium was not native (Silliman never wrote that it was native) but was chemically extracted from the ferberite pseudomorphs after scheelite that are unique to Lane's Mine of Trumbull. Silliman's tellurium extraction results were never repeated by another investigator.

Other Regions, Features and Areas containing this locality

References