Old Mine Park (Lane’s Mine of Trumbull; Lane's New Stratford mine; Hubbard Mine; Long Hill Mine; Old Tungsten Mine), Long Hill, Trumbull, Fairfield Co., Connecticut, USA
|Latitude & Longitude (WGS84):||41° 17' 21'' North , 73° 13' 38'' West|
|Latitude & Longitude (decimal):||41.28917,-73.22722|
|Köppen climate type:||Cfa : Humid subtropical climate|
This locality (a town park), like the neighboring Old Mine Plaza, is unique in Connecticut for its varied mineralogy and the area was prospected since the early 19th century. Although officially referred to as Tungsten Mine Park, the park encompasses a number of unrelated deposits with separate prospecting and mining history and mineralogy.
It is underlain by gently dipping, interlayered amphibolite and marble. The amphibolite, which surrounds the park area, is host to a stratiform deposit of scheelite. Within the park only, some of the scheelite at the contact with the marble is pseudomorphed by ferberite (all crystals tested are Fe-dominant and use of the term "wolframite" should be abandoned here), and was the subject of short-lived mining efforts around 1900. According to Sullivan (1985), this was after Ephraim Lane and later his son Charles, prospected it in the early to mid-1800s, and after Thomas Hubbard had searched in vain for copper, lead and silver deposits, not tungsten, in the late 1880s. According to Sullivan (1985), this site is also the first known North American topaz locality.
Sullivan also states that it should be the first tungsten deposit identified in North America (it was the first mined) and the correct type locality for tungstite, rather than the typically referenced Ephraim Lane's Mine in Monroe: http://www.mindat.org/loc-14012.html. Hobbs (1901) states that "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." These men were Ephraim and son Charles. No tungsten mineralization occurs at Lane's Mine in Monroe, the type tungstite occurs as an alteration of ferberite pseudomorphs and scheelite unique to the Trumbull mine (see specimens in Yale-Peabody Museum collection). Early reports by Silliman (1819a, 1819b, 1819c, 1821, 1822a, 1822b), Bowen (1822), and Hitchcock and Silliman (1826), which describe minerals initially attributed to Lane's Mine in Monroe, are actually describing minerals from the Trumbull deposit. This was eventually corrected by Hitchcock (1828) and is further discussed in Hitchcock (1835).
Mining of tungsten from scheelite in the amphibolite and the ferberite pseudomorphs after scheelite near the quartz-rich amphibolite/marble contact was undertaken by the American Tungsten Mining and Milling Company starting in 1899. They mined for a short time and built a mill that used a dry process that produced a 5% yield, but by 1902 they shut down because this process could not separate pyrite from the tungsten minerals (without additional roasting). A proven wet process was suggested by Gurlt, but not undertaken. The mine was also poorly laid out. The buildings lay idle until 1916 when they were destroyed by a fire. Had they realized that the scheelite apparently is present throughout the amphibolite, which is generally flat-lying and extends at least 1 km around their shaft (and well outside the park), a significant mine could have been developed. The town of Trumbull took the property in lieu of back taxes on October 4, 1937 and named it Old Mine Park on January 4, 1940 (Sullivan, 1985).
Numerous cross-cutting, steeply-dipping, +/-1m thick, hydrothermal veins crop out in the park and surrounding area. Their mineralogy varies but all show a similar metasomatic alteration of the host amphibolite to fine-grained, brownish phlogopite/marialite. The most common contain a core assemblage of coarse-grained quartz+/-topaz+/-fluorite var. chlorophane with a fine to medium-grained, sub-parallel muscovite (variety margarodite) wall zone. In some veins, the topaz, which may commonly have a coarse muscovite coating, has altered to a very soft, compact and granular to peripherally parallel-fibrous or lamellar habit of margarite (confirmed in 2014 using Raman spectroscopy). A predominantly quartz cored vein, called the Champion Lode, was mined for quartz for use in wood processing (Hobbs 1901, Trumbull Historical Society 1966). Some veins contain mostly albite+/-clinochlore+/-marialite. Very rare are calcite-cored veins with beryl and albite along the contact. Outcrops of the veins are generally small and the veins may in fact grade in composition between these extremes both laterally and vertically as some off-site veins show a mix of these compositions.
Later, brittle faulting and associated hydrothermal activity deposited purple to green fluorite, pyrite, pyrrhotite, tabular calcite in veins and fractures in a manner similar to that seen at the Thomaston Dam railroad cut.
Other minerals are found in the small marble quarries (amphiboles, pyroxenes, titanite, grossular, chlorite, phlogopite) and cross-cutting pegmatites (albite, microcline, quartz, muscovite, beryl). Veins and pods of plagioclase and scapolite are also present.
Sullivan reports other confusion through the years, such as topaz being called beryl (though it is present in the pegmatites), Hoadley's (1918) unconfirmed report of cronstedtite, zoisite (epidote, though the 'epidote' associated with the scheelite/ferberite is clinozoisite), and diaspore "mistakenly identified as euclase".
Commodity ListThis is a list of exploitable or exploited mineral commodities recorded at this locality.
57 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
419.2 - 443.8 Ma
|Basal member [of The Straits Schist]|
Age: Silurian (419.2 - 443.8 Ma)
Description: ( = Russell Mountain Formation of Massachusetts) - Distinguished by presence of layers of amphibolite, marble, calc-silicate rock, and quartzite within more uniform schist like that on either side. Minor, unevenly distributed mineralization in W, Bi, Cu, Ni, and other metals.
Comments: Part of Central Lowlands; Iapetus (Oceanic) Terrane - Connecticut Valley Synclinorium; Hartland Belt
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.