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Hale-Walker prospects, Collins Hill, Portland, Middlesex Co., Connecticut, USA

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Latitude & Longitude (WGS84): 41° 35' 7'' North , 72° 35' 17'' West
Latitude & Longitude (decimal): 41.58528,-72.58806
Köppen climate type:Dfa : Hot-summer humid continental climate


Two small prospects in narrow granitic pegmatite dike best known for its aquamarine. Minerals such as good epidote in quartz veins from the surrounding metamorphics are also included. According to Cameron et al (1954):

"The pegmatite...crops out on land owned jointly by Charles F. Walker, R. F. D., Portland, and Harry L. Walker, R. F. D., Glastonbury. It may extend eastward beneath overburden to land owned by Clifford Hale, R. F. D., Portland. In 1932 two small cuts were opened on the Walker property by the Eureka Flint & Spar Co., Portland, and were worked for 3 or 4 months for feldspar. According to Mr. William Wilkes, superintendent, about 70 tons of no. 1 feldspar was recovered. Both quarries have since been idle. The upper opencut is 25 feet long, 9 feet wide, and 1 to 10 feet deep. The lower opencut is 38 feet long, 10 feet wide, and 5 to 18 feet deep. Both pits are free of water and probably contain little backfill. The prospect was mapped by E. N. Cameron and V. E. Shainin in May 1943."

The pegmatite is a tabular body at least 180 feet long and 6 to 8 feet thick. It ranges in strike from N. 79° W. to east and dips 63° to 74° SW. The dike is sharply discordant to the enclosing granite-gneiss (Monson gneiss), whose foliation strikes N. 20° W. and dips westward at moderate to steep angles. The contact between the Monson gneiss and the Bolton schist lies 60 feet west of the westernmost exposure of the pegmatite. The pegmatite does not seem to extend across the contact.

The dike, a disseminated type of beryl deposit, consists chiefly of quartz and perthite. It has a border zone and a core. The border zone is ½ to 1 inch thick and is composed of fine-grained quartz, plagioclase and tourmaline. The core consists of medium- to coarse-grained quartz and perthite with subordinate amounts of plagioclase, muscovite, and accessory beryl, tourmaline, columbite-tantalite and monazite. Monazite is rare.
Most of the beryl occurs in the core, either with small anhedral crystals of perthite scattered in a matrix of coarse quartz, plagioclase and accessory tourmaline, or with fine-grained quartz, plagioclase, and accessory tourmaline.

The beryl is green to blue-green and occurs in crystals 0.2 to 2 inches long and 0.1 to 2 inches in diameter, but most of the crystals are very small.


Mineral List


19 valid minerals. 2 erroneous literature entries.

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 Macrostrat.org

Late Ordovician - Middle Ordovician
443.8 - 470 Ma



ID: 2978277
Collins Hill Formation

Age: Ordovician (443.8 - 470 Ma)

Stratigraphic Name: Collins Hill Formation

Description: ( = Partridge Formation of New Hampshire) - Gray, rusty-weathering, medium- to coarse-grained, poorly layered schist, composed of quartz, oligoclase, muscovite, biotite, and garnet, and commonly staurolite, kyanite, or sillimanite, generally graphitic, interlayered with fine-grained two-mica gneiss, especially to the west, and with calc-silicate and amphibolite layers, also rare quartz-spessartine (coticule) layers.

Comments: Part of Eastern Uplands; Iapetus (Oceanic) Terrane - Bronson Hill Anticlinorium; Brimfield Schist and equivalent formations (includes Collins Hill Formation) (Upper? and Middle Ordovician).

Lithology: Major:{schist}, Minor:{gneiss}, Incidental:{amphibolite, calc silicate rock}

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 Macrostrat.org, used under Creative Commons Attribution 4.0 License



This page contains all mineral locality references listed on mindat.org. 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 mindat.org 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.

References

Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Cameron, Eugene N., Larrabee David M., McNair, Andrew H., Page, James T., Stewart, Glenn W., and Shainin, Vincent E. (1954): Pegmatite Investigations 1942-45 New England; USGS Professional Paper 255.
Schooner, Richard. (1955): 90 Minerals from 1 Connecticut Hill. Rocks and Minerals, vol. 30, no. 7-8, pp. 351-8.
Schooner, Richard. (1958): The Mineralogy of the Portland-East Hampton-Middletown-Haddam Area in Connecticut (With a few notes on Glastonbury and Marlborough). Published by Richard Schooner; Ralph Lieser of Pappy’s Beryl Shop, East Hampton; and Howard Pate of Fluorescent House, Branford, Connecticut.
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. Fluorescent House, Branford, Connecticut.
Ryerson, Kathleen. (1972): Rock Hound's Guide to Connecticut. Pequot Press.
Januzzi, Ronald. (1976): Mineral Localities of Connecticut and Southeastern New York State (Taylor Assoc./Mineralogical Press).
Albini, Anthony J. (1979): Selected Pegmatite Quarries of the Central Connecticut Region. Masters thesis. Central Connecticut State College, New Britain, Connecticut
Webster, Bud and Bill Shelton. (1979): Mineral Collector’s Field Guide the Northeast.
Weber, Marcelle H. and Earle C. Sullivan. (1995): Connecticut Mineral Locality Index. Rocks & Minerals (Connecticut Issue), Vol. 70, No. 6, p. 403.

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