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Canton Lead Mines (Cherry Brook lead mine; Dyer Farm zinc mine), Rattlesnake Mountain, Canton, Hartford Co., Connecticut, USAi
Regional Level Types
Canton Lead Mines (Cherry Brook lead mine; Dyer Farm zinc mine)Group of Mines
Rattlesnake MountainMountain
Canton- not defined -
Hartford Co.County

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Lock Map
Latitude & Longitude (WGS84): 41° 50' 9'' North , 72° 54' 47'' West
Latitude & Longitude (decimal): 41.83611,-72.91306
GeoHash:G#: drknhb434
Locality type:Group of Mines
Köppen climate type:Dfa : Hot-summer humid continental climate

Very little has been written about this old locality, most references give only the briefest mention. A 1910 postcard shows what was called the zinc mine on the Dyer Farm, Collinsville, Conn. The 1869 map of Canton shows a house owned by "D. Dyer" on the road close to the mine location. The Town of Canton web site (see link below) gives a brief history of the Dyer house and property at 1 Dyer Cemetery Road, near the same spot, that had "...a farm of six hundred acres. Over the years it had a sawmill; “silver mine” that produced small quantities of zinc, lead, copper and beryl..." Given the size of the farm and the proximity of the house with the mine, the mine in the postcard must be the Canton lead mine.

Shepard (1837) presaged, or perhaps inspired, the mining of lead here with this short sentence:

Rolled masses [boulders] of quartz including galena have been found in Canton near Collinsville...indicating the existence of veins of such ores in these regions.

A hydrothermal fault vein deposit, probably related to Mesozoic rifting as large-scale faults associated with the Hartford and Cherry Brook rift basins are close by. Minor amounts of galena, sphalerite, and lead secondary minerals occur here. But the locality is most famous for its amethyst, which occurs lining cavities in breccia and varies from larger lavender, mottled and translucent crystals to smaller, clearer, deeply colored druses. Colorless and milky quartz also occurs. Any beryl found must be related to a pegmatite in the host rock that the mine intersected.

Select Mineral List Type

Standard Detailed Strunz Dana Chemical Elements

Commodity List

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

Mineral List

7 valid minerals.

Detailed Mineral List:

Formula: PbCO3
Colour: pale gray to pale yellow-orange
Fluorescence: orange-yellow
Description: small, irregular, resinous crystals on quartz
Reference: Ronald Januzzi collection
Formula: CuFeS2
Habit: anhedral
Colour: brassy yellow
Description: tiny grains in massive quartz with other sulfides
Reference: Marcelle Weber collection
Formula: PbS
Habit: cubic
Colour: steel-gray
Description: typically cubes and masses frozen in quartz
Reference: Rocks & Minerals (1995) 70:396-409; Hiller (1971)
Formula: Pb
Reference: From USGS MRDS database
Formula: Pb5(PO4)3Cl
Habit: acicular hexagonal
Colour: green
Description: "scanty green coatings of tiny hexagonal crystals" Schooner (1961)
Reference: Rocks & Minerals (1995) 70:396-409; Schooner (1961)
Formula: SiO2
Habit: stubby parallel crystals or individual elongated prisms
Colour: colorless to milky white to lightly smoky
Description: banded columnar masses lining pockets in breccia grade into amethyst, individual elongated crystals up to 17 cm
Reference: Schooner (1961) Mineralogy of Connecticut
Quartz var: Amethyst
Formula: SiO2
Habit: stubby parallel prisms lining pockets
Colour: lavender, purple
Description: Cavities in breccia are lined with parallel crystals of ordinary quartz or amethyst. Much cutting quality amethyst has been obtained there. Some is distinctly zoned. Larger crystals are typically paler colored, translucent, typically have mottled appearance. Smaller crystals typically clearer and deeply colored.
Reference: Kenneth Holt specimen (locality info corrected courtesy of John Betts); Mineralogical Record (1990) 21:203-213; Rocks & Minerals (1995) 70:396-409
Quartz var: Milky Quartz
Formula: SiO2
Reference: John Burnham
Quartz var: Smoky Quartz
Formula: SiO2
Reference: John Burnham
Formula: ZnS
Habit: massive
Colour: black, brown, yellow
Reference: Schooner (1961) Mineralogy of Connecticut
Formula: Pb(MoO4)
Habit: tabular
Colour: orange
Description: "Tiny orange crystals are occasionally observed on quartz crystals and metallic ores...usually associated with pyromorphite" Schooner (1961)
Reference: Rocks & Minerals (1995) 70:396-409; Schooner (1961)
Formula: Zn
Reference: From USGS MRDS database

List of minerals arranged by Strunz 10th Edition classification

Group 2 - Sulphides and Sulfosalts
Group 4 - Oxides and Hydroxides
var: Amethyst4.DA.05SiO2
var: Milky Quartz4.DA.05SiO2
var: Smoky Quartz4.DA.05SiO2
Group 5 - Nitrates and Carbonates
Group 7 - Sulphates, Chromates, Molybdates and Tungstates
Group 8 - Phosphates, Arsenates and Vanadates

List of minerals arranged by Dana 8th Edition classification

Group 2 - SULFIDES
AmXp, with m:p = 1:1
AmBnXp, with (m+n):p = 1:1
Group 75 - TECTOSILICATES Si Tetrahedral Frameworks
Si Tetrahedral Frameworks - SiO2 with [4] coordinated Si
Unclassified Minerals, Rocks, etc.
var: Amethyst-SiO2
var: Milky Quartz-SiO2
var: Smoky Quartz-SiO2

List of minerals for each chemical element

C CerussitePbCO3
O Quartz (var: Amethyst)SiO2
O CerussitePbCO3
O Quartz (var: Milky Quartz)SiO2
O PyromorphitePb5(PO4)3Cl
O QuartzSiO2
O Quartz (var: Smoky Quartz)SiO2
O WulfenitePb(MoO4)
Si Quartz (var: Amethyst)SiO2
Si Quartz (var: Milky Quartz)SiO2
Si QuartzSiO2
Si Quartz (var: Smoky Quartz)SiO2
P PyromorphitePb5(PO4)3Cl
S ChalcopyriteCuFeS2
S GalenaPbS
S SphaleriteZnS
Cl PyromorphitePb5(PO4)3Cl
Fe ChalcopyriteCuFeS2
Cu ChalcopyriteCuFeS2
Zn SphaleriteZnS
Mo WulfenitePb(MoO4)
Pb CerussitePbCO3
Pb GalenaPbS
Pb PyromorphitePb5(PO4)3Cl
Pb WulfenitePb(MoO4)

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

201.3 - 251.902 Ma

ID: 3188891
Mesozoic volcanic and intrusive rocks

Age: Triassic (201.3 - 251.902 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: 2927585
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. Original map source: Connecticut Geological and Natural History Survey, DEP, in cooperation with the U.S. Geological Survey, 2000, Bedrock Geology of Connecticut, shapefile, scale 1:50,000

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 Macrostrat.org, used under Creative Commons Attribution 4.0 License


Sort by

Year (asc) Year (desc) Author (A-Z) Author (Z-A)
Shepard, Charles Upham. (1837), Report on the Geological Survey of Connecticut.
Schairer, John F. (1931), Minerals of Connecticut. State Geological and Natural History Survey of Connecticut Bulletin 51.
Schooner, Richard. (1961), The Mineralogy of Connecticut. Fluorescent House, Branford, Connecticut.
Hiller, John, Jr. (1971), Connecticut Mines and Minerals. Privately published.
White, John, and Cook, Robert. (1990), Amethyst Occurrences of the Eastern United States. Mineralogical Record: 21(3): 203-213.
Weber, Marcelle H. and Earle C. Sullivan. (1995), Connecticut Mineral Locality Index. Rocks & Minerals (Connecticut Issue): 70(6): 399.

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