Latitude: 41°31'58"N
Longitude: 72°36'37"W
A granite pegmatite quarried on and off since perhaps 1825 for mica and feldspar. It was called the "china-stone quarry" by Shepard (1837) and by 1850 it featured the first feldspar grinding mill in the United States (Cameron et al, 1954). Most of the mining is said to have been done for feldspar and mica prior to 1896, but intermittent operations were conducted between 1896 and 1926. Watts (1916) called it the Bidwell Quarry and Cameron et al (1954) noted that in the 1940s it was still owned by Ernest S. Bidwell. Fausto Bertolini of New Haven, Conn., worked the mine for mica and feldspar from July 1943 to January 1945.
The name Tollgate refers to the quarry's proximity to the old Middlesex Turnpike toll road (1802-1876), which later became state Route 9, then 9A, and finally 154. Foye (1922) is the first reference to use that name, by which it has been known ever since.
Perhaps best known for
columbite-(Fe), Shepard (1837) described this early find: "The china-stone quarry at Middletown has furnished the most extraordinary specimens of columbite yet described in the world. A single group of crystals obtained at this place weighed fourteen pounds. It occurs in crystals disseminated through the feldspar, many of which are very remarkable, not only for their size, but for their perfection of form." A 7 x 7 inch portion of it weighing nearly 13 pounds was purchased by Wesleyan University. Crystals from this quarry were used during the 19th century by many researchers to eventually work out the chemistry of the columbite-tantalite series. Dana (1837, 1856 and 1857) provided analyses showing that the Middletown crystals are columbite-(Fe). Some authors speculate that the first columbite crystal, found by Governor Winthrop in the mid-17th century and eventually analyzed in Britain by Hatchett in 1802, came from this pegmatite.
According to Cameron (1954) surface workings in 1945 consisted of an open pit 350 feet long, 65 feet in average width, and 30 feet in average depth. Underground workings consist of two inclines, each 45 feet long, and two drifts, each 40 feet long. In the early 1990s the quarry was filled when a church was built on the property.
Cameron et al (1954) gives the most detailed description of the pegmatite:
"The pegmatite is a tabular lens with irregular walls. It is at least 500 feet long and has been mined for a maximum distance of 140 feet down dip. It ranges from 4 inches to 60 feet in thickness, and averages 20 to 25 feet. The pegmatite strikes north-south and dips 50° W; it seems to terminate just north of the workings. It is concordant with the foliation and bedding of fine- to medium-grained quartz-muscovite-biotite schist that has layers of fine-grained quartzite, 1 to 6 inches thick. The wall rock adjacent to the contact is rich in tourmaline and garnet.
The border zone, 1 to 7 inches thick, consists of fine-grained quartz and muscovite with minor massive white plagioclase. The wall zone, 1 to 6 feet thick, consists of fine- to coarse-grained milky quartz, white plagioclase (locally
cleavelandite) and accessory sheet-bearing muscovite, [microcline] perthite and garnet.
The quartz-[microcline] perthite zone is coarse-grained. It consists of quartz and [microcline] perthite, with subordinate plagioclase and muscovite, and accessory biotite [annite], apatite, garnet, tourmaline, columbite-tantalite,
autunite and
torbernite. The outer part of the zone - adjacent to the wall zone - seems to be richer in plagioclase and perhaps, if better exposures were available, the quartz-[microcline] perthite zone could be divided into 2 zones. Pods of milky quartz as much as 4 by 30 feet lie in the quartz-[microcline] perthite zone. Mica books of poor quality lie near the margins of some pods. Apatite occurs in aggregates of subhedral pale green crystals that average 1/4 inch in diameter. The aggregates are 3 inches to 2 feet in diameter and occur chiefly in [microcline] perthite masses. Almost all of them contain subhedral plates of columbite-tantalite 1/8 to 1 inch long."
References
- Silliman, Benjamin. (1836): Notice of a Large Crystal of Columbite. American Journal of Science, s.1, vol. 30, p. 387-388.
- Dana, J. D. (1837): On the Identity of Torrelite of Thomson with Columbite. American Journal of Science. Series 1, Vol. 32, p. 149-153.
- Shepard, Charles U. (1837): Report on the Geological Survey of Connecticut.
- Shepard, Charles U. (1838). Notice of a Second Locality of Topaz in Connecticut, and of the Phenakite in Massachusetts (Am. Jour. of Sci. 34:329-331).
- Silliman, Benjamin. (1851): Mineral Species Described by Prof. C. U. Shepard. Marasmolite. American Journal of Science, s.2, v. 12, p. 210.
- Dana, James D. (1856): Supplement to the Mineralogy of J. D. Dana. American Journal of Science, s. 2, v. 21, p. 198.
- Dana, James D. (1857): 4th Supplement to Dana's Mineralogy. American Journal of Science, s. 2, v. 24, p. 115.
- Watts, A. S. (1916): Feldspars of New England and North Appalachian States. United States Bureau of Mines. Bulletin 92.
- Foye, W. G. (1922): Mineral Localities in the Vicinity of Middletown, Connecticut. (American Mineralogist 7:4-12)
- Rice, William North, and Wilbur Garland Foye. (1927): Guide to the Geology of Middletown, Connecticut, and Vicinity. State Geological and Natural History Survey. Bulletin 41.
- Cameron, Eugene N. and others. (1954): PEGMATITE INVESTIGATIONS 1942-45 NEW ENGLAND. U.S. Geological Survey, Professional Paper 255.
- Schooner, Richard. (1958): THE MINERALOGY OF THE PORTLAND-EAST HAMPTON-MIDDLETOWN-HADDAM AREA IN CONNECTICUT (With a few notes on Glastonbury and Marlborough).
- Stugard, Frederick, Jr. (1958): PEGMATITES OF THE MIDDLETOWN AREA, CONNECTICUT. USGS Bulletin 1042-Q.
- Jones, Robert W. (1960): LUMINESCENT MINERALS OF CONNECTICUT, A GUIDE TO THEIR PROPERTIES AND LOCATIONS.
- Schooner, Richard. (1961): THE MINERALOGY OF CONNECTICUT.
- Henderson, William A., Jr. (1975): The Bertrandites of Connecticut. The Mineralogical Record, Volume 6, Number 3, pages 114-123.
- Januzzi, Ronald. (1976): Mineral Localities of Connecticut and Southeastern New York State (Taylor Assoc./Mineralogical Press).
- Weber, Marcelle H. and Earle C. Sullivan. (November/December 1995): CONNECTICUT MINERAL LOCALITY INDEX. Rocks & Minerals (Connecticut Issue), Volume 70, No. 6, p. 403.
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