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Bristol Copper Mine, Bristol, Hartford Co., Connecticut, USA

This page kindly sponsored by Jim Spann
Latitude & Longitude (WGS84): 41° 43' 9'' North , 72° 55' 26'' West
Latitude & Longitude (decimal): 41.71917,-72.92389
Köppen climate type:Dfa : Hot-summer humid continental climate

A copper mine situated on the western border fault of the central Connecticut Mesozoic Hartford Basin. Commercial mining began in 1837 and carried on intermittently until 1953. World class specimens of chalcocite and bornite were saved, mainly in the late 1840s (to the consternation of some operators) and are in many museum and private collections. Bateman (1923) provides a good summary:

The mine lies at an elevation of 350 feet near the northern line of the town of Bristol, Connecticut, and about four miles from its center. It is on the contact between the red Triassic sandstone of the Farmington River Valley and the crystalline rocks of the western upland. The former gives rise to a flattish topography and the latter is bordered by a line of rolling hills, here and there marked by steep faces, which in the vicinity of the mine rise to an elevation of 650 feet.

In the earlier part of the nineteenth century the State of Connecticut boasted of a number of mines, and the Bristol mine ranked first among the copper properties. It is reported to have been discovered in 1836 and was first described by Shepard in 1837. Mention was also made of it by Percival in 1842.

Prior to 1847 it was worked in a desultory way and there was shipped to England about 125 tons of high-grade ore. From 1847 to 1853 it was more vigorously worked. During this period some half million dollars was spent upon the property; workings were extended to a depth of 240 feet and to a maximum distance of 500 feet along the vein and 120 feet across.

During this same period, nearly $200,000 was obtained from about 2,200 tons of picked ore with an average copper content of 33 per cent. Some time after this the mine was closed. It was again opened in 1888 and a new shaft was sunk in the sandstone to a depth of 378 feet. Levels were run to depths of 30, 40, 50, and 60 fathoms, respectively, each one of which traversed the sandstones lying between the shaft and the contact, and penetrated into the schists...The mill was rebuilt and considerable mining activity took place until 1895 since which time the property has been idle. There are data available as to the amount of copper that was produced during this period, but several thousand tons of tailings on the dumps indicate a considerable extraction of ore.

The principal opening of the mine is a large pit some 100 feet or so in diameter, which represents a portion of the mine that has caved in. It is now filled by water. Two working shafts are visible. One is 125 feet from the schist-sandstone contact in the sandstone, and is said to be 240 feet deep. The other shaft lies 225 feet further eastward in the sandstone area, and is 378 feet deep...None of the workings are accessible at the present time. Another shaft, said to be 100 feet deep lies some 500 feet to the south. In addition to the main open cut, old prospect holes, shafts, and tunnels may be seen to the northeast, along what is presumably the contact. Everything is now covered with vegetation so that little can be seen.

Afterward the mine was idle for decades with one last attempt in 1947-1953 as summarized by Jones (2001):

The world wars had brought on copper shortages and high copper prices, and Allen Hearst of Forestville, Connecticut, convinced himself, both that there were still significant ore reserves in the Bristol mine, and that 20th-century technology could profitably extract copper even from low-grade ores at Bristol.

Hearst formed the Connecticut Mining and Milling Company with the express purpose of extracting silver and copper from the tailings on the site. He also undertook some limited dewatering and building. But the fall of world copper prices from their wartime highs finally saw to it that the venture was not successful; the mine was abandoned again in 1953. The property, zoned for industrial use, is now leased by a fuel oil company with a portion of the property used for a rubble dump and equipment storage site. The shafts have been filled and sealed, and access to the underground workings of the deposit will probably never again be possible.

Jones (2001) provides perspective on the famous specimens:

Bristol offers much of historical interest as well. The mine property was originally owned by the Yale family, after whom Yale University is named. During the period of major development in the mid-19th century, several prominent Yale people were involved in the ownership and operation of the mine. These included Benjamin Silliman Sr. and Jr., James Dana Whitney, and John M. Woolsey. The English-born Charles M. Wheatley of New York, later to manage and give his name to the famous Wheatley lead mines at Phoenixville, Pennsylvania, came on as manager of the Bristol mine just as the great chalcocite and bornite specimens were about to be discovered. Wheatley, Whitney and Benjamin Silliman Jr. all protested vehemently against the mine owners’ wishes to process fine crystal specimens as ore, and are no doubt responsible for the preservation of most of the best specimens that have survived....

These miners reportedly found the Bristol orebody to be reminiscent of those at Truro, Redruth and Penzance, Cornwall. In the late 1840’s the “Cousin Jacks” would be on hand for the discovery of vugs lined with crystallized chalcocite, and may have troubled to preserve many specimens. Dr. Steven Chamberlain of Syracuse, New York, has reported that when he visited numerous private collections in Cornwall, England, over a hundred years later, “he observed, unexpectedly, a number of fine Bristol chalcocites which had been assigned a Cornwall pedigree,” apparently brought or sent home by Cornish miners (Heitner and Lininger, 1997)...

In 1847...Major stockholders included Yale people such as John M. Woolsey, Josiah D. Whitney, and Professor Benjamin Silliman, Jr. - son of Benjamin Silliman, Sr., the great mineralogist who “almost single-handedly took Yale into pre-eminence in early American education in chemistry, geology and mineralogy” (Moore, 1999). This connection with the Sillimans of Yale would prove fortuitous for Bristol and its great mineral specimens.

The position of mine manager went to 24-year-old Charles Moore Wheatley. Although already a successful businessman, Wheatley had only an amateur naturalist’s interest in geology and mineralogy, and no experience in mine management. However, his quick intelligence, enthusiasm, hard work, and dedication to mineralogy soon won him the support and respect of Benjamin Silliman, Jr. The warm relationship would pay continuing dividends for the Peabody Collection at Yale when Wheatley later took charge of the lead mines at Phoenixville, Pennsylvania, which now bear his name, and sent many fine specimens from there to Silliman in New Haven. Unfortunately, his tenure at Bristol lasted only until 1849, when he left to work at the Perkiomen and Ecton mines in Pennsylvania (Evans, 1984).

Under the leadership of its new cadre, the Bristol mine flourished, and soon was rated the most important copper mine in the northeastern United States (Smith and Smith, 1907)...

Many of the historically important specimens now in the Yale-Peabody collection certainly came to light at this time. A large number of fine chalcocite specimens also went to Union College, which is not surprising considering that Eliphalet Nott was president of that institution while also heading the Bristol Mining Company in the late 1840’s. Many more fine chalcocites also went to Union College in 1858, when Charley Wheatley sold his collection to the school, Josiah Whitney having arranged the sale...

The 1850’s saw a major disagreement among the owners and managers of the mine about what to do with the fine crystal specimens being found. Most of the owners wanted the specimens simply sent to the stamp mill to increase the yield, but Silliman (?) objected strongly. Hurlbert (1897), describing the management of the mine during 1855-1857, writes “It was during this administration that specimens of chalcocite of peculiar form could have been easily sold as cabinet specimens for hundreds of dollars, [but] were crushed for ore in spite of the protest of the mineralogist.” Heitner and Lininger (1997) speculate that this “mineralogist” was Benjamin Silliman, Jr., or possibly Josiah Whitney or Ludwig Stadtmüller. It was perhaps in part to protest the fate of these specimens that Silliman and Whitney sold out their holdings at the same time as did Nott - in 1857. Their reason also may have been the financial extravagance of Henry R. Sheldon, hired in 1851 as mine manager and bringing with him a Cornishman, Captain Williams, to oversee the property and production.

Commodity List

This is a list of exploitable or exploited mineral commodities recorded at this locality.

Mineral List

23 valid minerals.

Regional Geology

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

201.3 - 252.17 Ma

ID: 3188891
Mesozoic volcanic and intrusive rocks

Age: Triassic (201.3 - 252.17 Ma)

Comments: Connecticut Valley Basin

Lithology: Mafic volcanic rocks; conglomerate,arkose,shale,arenite

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. [154]

Middle Ordovician
458.4 - 470 Ma

ID: 2944975
Sweetheart Mountain Member [of Collinsville Formation]

Age: Middle Ordovician (458.4 - 470 Ma)

Stratigraphic Name: Sweetheart Mountain Member

Description: Gray and silvery (not rusty), medium- to coarse-grained, poorly layered schist, composed of quartz, oligoclase, biotite, muscovite, and garnet, and in places kyanite or sillimanite. Amphibolite layers common; also layers of quartz-spessartine rock (coticule). In the Bristol quad., CT, Collinsville Formation is revised to include a basal unnamed hornblende gneiss member (was upper part of Stanley's (1964) Bristol Member), a middle unnamed metaquartzite member, and the upper Sweetheart Mountain Member. Bristol Member of Stanley (1964) is raised in rank to Bristol Gneiss in the report area. Collinsville unconformably underlies The Straits Schist. Inferred age is Middle Ordovician (Simpson, 1990).

Comments: Part of Central Lowlands; Iapetus (Oceanic) Terrane - Connecticut Valley Synclinorium; Gneiss Dome Belt, Hawley Formation and equivalent formations (includes Collinsville Formation) (Middle Ordovician). Secondary unit description per CT008.

Lithology: Major:{schist}, Minor:{amphibolite}, Incidental:{metamorphic}

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. [133]

Data and map coding provided by, used under Creative Commons Attribution 4.0 License

This page contains all mineral locality references listed on This does not claim to be a complete list. If you know of more minerals from this site, please register so you can add to our database. This locality information is for reference purposes only. You should never attempt to visit any sites listed in without first ensuring that you have the permission of the land and/or mineral rights holders for access and that you are aware of all safety precautions necessary.


Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Shepard, Charles U. (1837): Report on the Geological Survey of Connecticut. B. L. Hamlem, New Haven.
Percival, J. G. (1842): Report on the Geology of the State of Connecticut. Connecticut Geological Survey, New Haven.
Shepard, Charles U. (1844): A Treatise on Mineralogy. New Haven.
Shepard, Charles U. (l852): A Treatise on Mineralogy. New Haven.
Richardson. C. S. (1854a): The Hartford Mining Company’s property at Bristol, Connecticut. Mining Magazine: 2(Jan—June): 490—493.
Richardson, C. S. (1854b): The Old Bristol copper mine. Connecticut. Mining Magazine: 3:(July—Dec): 251—255.
Silliman, Benjamin and Whitney, J. (1855a): Report of an Examination of the Bristol Copper Mine, in Bristol, Connecticut. Ezekiel Hayes, New Haven.
Silliman, Benjamin and Whitney, J. (1855b): Notice of the Geological Position and Character of the Copper Mine at Bristol, Conn. American Journal of Science: series 2, 20: 361-368.
Tenny. W. J.. ed. (1855): The Bristol Copper Company. Mining Magazine: 5(July—Dec): 173—174.
Tenny. W. J., ed. (1856): Journal of Copper Mining Operation, The Bristol Copper Mine. Mining Magazine: 6(Jan—July): 86— 91, 185—188.
Gaussoin, E. (1864): The Bristol Copper Mines. J. B. Rose and Co., Baltimore.
Dana, Edward S. (1892): System of Mineralogy, 6th. Edition. Wiley & Sons, New York: 693.
Hurlbert, E. M. (1897): Copper Mining in Connecticut. The Connecticut Quarterly: 3(1): 23—32.
Smith. E. N. and Smith, G. B. (1907): Bristol, Connecticut in Olden Times. New Cambridge City Printing Company, Hartford, Connecticut.
Weed, Walter H. (1911): Copper Deposits of the Appalachian States. USGS Bulletin 455.
Bateman, Alan M. (1923): Primary Chalcocite: Bristol Copper Mine Connecticut. Economic Geology: 18:122-166.
Schairer, John F. (1931): Minerals of Connecticut. Connecticut Geological and Natural History Survey Bulletin 51.
Elwell, Wilbur J. (1936): A Mineralogical Trip Through New England. Rocks and Minerals: 11(3): 36-7.
Elwell, Wilbur. (1937): Some Old Localities in Connecticut. Rocks and Minerals: 12(9): 270-1.
Harte, Charles R. (1944): The Bristol Copper Mine. 60th Annual Report of the Connecticut Society of Civil Engineers: 149-153.
Schooner, Richard. (1961): The Mineralogy of Connecticut. Fluorescent House, Branford, Connecticut.
Ryerson, Kathleen. (1972): Rockhound’s Guide to Connecticut. Pequot Press, Cheshire, Connecticut.
Perry, G. R. (1975): Bristol’s Copper Mines and Quarries. Greater Bristol Historical Society Newsletter 2, November 1975.
Domonell, W. G. (1991): A History of Copper Mining in Bristol. The Connecticut Historical Society Bulletin: 56(1—2): 5—37.
Weber, Marcelle H. and Earle C. Sullivan. (1995): Connecticut Mineral Locality Index. Rocks & Minerals (Connecticut Issue): 70(6): 398.
Heitner, H., and Lininger, J. (1997): The Chalcocite Crystals of Bristol, Connecticut: The History of a Classic American Mineral Location. Matrix: 5(2):51-67.
Jones, Robert W. (2001): Famous Mineral Localities: The Bristol Copper Mine Connecticut. Mineralogical Record: 32(6):433-450.
Czerwinski, Leslie C. (2010): Copper Mining in Bristol Connecticut - The Impact of a Natural Resource on Local Society. Wesleyan University Master of Arts thesis.

External Links - Chalcocite crystal figures in Dana's System of Mineralogy, 4th edition. (1854). - Nail-head calcite crystals; James D. Dana in American Journal of Science 18:421 (1854)

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