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Long Hill prospects (Turkey Hill prospects), Haddam, Middlesex Co., Connecticut, USAi
Regional Level Types
Long Hill prospects (Turkey Hill prospects)Group of Prospects
Haddam- not defined -
Middlesex Co.County

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Latitude & Longitude (WGS84):
41° 27' 4'' North , 72° 30' 20'' West
Latitude & Longitude (decimal):
Locality type:
Group of Prospects
Köppen climate type:
Nearest Settlements:
East Haddam9,042 (2017)3.7km
Higganum1,698 (2017)6.7km
Chester Center1,558 (2017)7.1km
Moodus1,413 (2017)7.4km
Deep River Center2,484 (2017)9.5km

Often erroneously referred to as Turkey Hill, which is further south, Long Hill hosts many very small beryl prospects in narrow, zoned pegmatites. Hall (1840) describes specimens obtained from the gneiss quarries on Long Hill, though the emerald color is a bit of an exaggeration:

I have just procured two of the finest crystals I ever had in my possession. One of them is a perfect hexagonal prism, about two inches long, and an inch and a half in diameter. The faces forming its terminations are at right angles with the sides, and wear as fine a polish as the hand of Nature can produce. The color is a brilliant emerald green, and, indeed, the crystal appears to possess more of the characters of the emerald, than of the beryl.

The prospects are scattered widely, so the reference coordinates given below are for the summit. The following description from Barton and Goldsmith (1968) is the best and most comprehensive:

The Long Hill prospects are located in Haddam about 12 miles S 20° E from the center of town (fig. 31). They are on 160 acres owned by Mrs. Sona Keirstead which includes the crest of Long Hill. Numerous small prospect pits have been dug by mineral collectors but no organized beryl mining has been attempted. There are several small quarries on the hill which were worked for gneiss dimension stone many years ago.

Beryl occurs in numerous small pegmatite dikes cutting both the hornblende-biotite gneisses and the small concordant quartz veins associated with the gneisses on Long Hill. The gneiss banding and the quartz veins strike N 17° W and dip 75° E. The cross-cutting pegmatite dikes strike an average N 40° E, and dip 65°-75° SE. The exposed dikes (as seen in some of the old stone quarries) are small, up to 8 feet wide by 40 feet long, and are emplaced in a typical en echelon pattern. Gem beryl (green to blue) appears to be an ubiquitous dike constituent. In some of the better exposures beryl appears to comprise 1 percent of the pegmatite mass. Most of the pegmatites, however, are poorly exposed, showing only in small rubble filled pits where prospectors set off a single dynamite charge. The pits are numerous and widely scattered and, coupled with abundant quartz-perthite pegmatite float on the ridge line of Long Hill, indicate that one or several other pegmatites may be concealed beneath overburden. However, no exploration was attempted to evolve an answer to this question.

Exposed pegmatites are fairly well zoned but zoning is not entirely consistent from one pegmatite to the next.

London (1989) notes that most of these unfoliated pegmatites strike discordantly east-west, display sharp contacts, and are muscovite and tourmaline rich with a composition mostly of microcline and quartz, with quartz rich cores. Some have accessory beryl and garnet. This is in contrast to what he maps as "syenitic feldspar pegmatite" which are concordant, weakly foliated, unzoned and contain more abundant albite but lack accessory minerals other than micas and garnet.

Regions containing this locality

North America PlateTectonic Plate

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

11 valid minerals.

Detailed Mineral List:

Formula: Na(AlSi3O8)
Habit: anhedral
Colour: white
Description: Stugard (1958) established through sampling of many pegmatites in the district that the plagiocalse component of pegmatites in the Middletown district is albite.
Reference: Stugard (1958)
Formula: Fe2+3Al2(SiO4)3
Habit: trapezohedral in pegmatites, dodecahedral in metamorphic rocks
Colour: maroon, red
Description: In pegmatites and metamorphic rocks.
Reference: Harold Moritz collection
Formula: Be4(Si2O7)(OH)2
Reference: Mineralogical Record (1975) 6:114-123
Formula: Be3Al2(Si6O18)
Habit: Hexagonal prism with pinacoidal terminations.
Colour: green, blue
Reference: Rocks & Minerals (1995) 70:396-409
Beryl var: Aquamarine
Formula: Be3Al2Si6O18
Reference: Harold Moritz collection
Formula: Bi2S3
Habit: acicular
Colour: silver-gray
Reference: Rocks & Minerals (1995) 70:396-409
Formula: K(AlSi3O8)
Colour: white
Description: Stugard (1958) established through sampling of many pegmatites in the district that the plagiocalse component of pegmatites in the Middletown district is albite. Crystals contacting the quartz cores of these pegmatites are euhedral toward the core.
Reference: Stugard (1958)
'Microlite Group'
Formula: A2-mTa2X6-wZ-n
Reference: Harold Moritz collection
Formula: MoS2
Habit: massive platy
Colour: metallic silvery gray
Reference: Joe Webb Peoples Museum, Exley Science Ccenter, Wesleyan University, Middletown, Connecticut, USA
Formula: KAl2(AlSi3O10)(OH)2
Habit: anhedral
Colour: silvery
Reference: Harold Moritz collection
Formula: SiO2
Reference: Rocks & Minerals (1995) 70:396-409
Quartz var: Smoky Quartz
Formula: SiO2
Habit: anhedral
Colour: gray
Reference: Harold Moritz collection
Formula: Na(Fe2+3)Al6(Si6O18)(BO3)3(OH)3(OH)
Habit: trigonal prisms with rhombohedral terminations
Colour: black
Reference: Harold Moritz collection
Formula: Al2(SiO4)(F,OH)2
Reference: Rocks & Minerals (1995) 70:396-409

List of minerals arranged by Strunz 10th Edition classification

Group 2 - Sulphides and Sulfosalts
Group 4 - Oxides and Hydroxides
'Microlite Group'4.00.A2-mTa2X6-wZ-n
var: Smoky Quartz4.DA.05SiO2
Group 9 - Silicates
var: Aquamarine9.CJ.05Be3Al2Si6O18

List of minerals arranged by Dana 8th Edition classification

Group 2 - SULFIDES
AmBnXp, with (m+n):p = 2:3
AmBnXp, with (m+n):p = 1:2
'Microlite Group'
Group 51 - NESOSILICATES Insular SiO4 Groups Only
Insular SiO4 Groups Only with cations in [6] and >[6] coordination
Group 52 - NESOSILICATES Insular SiO4 Groups and O,OH,F,H2O
Insular SiO4 Groups and O, OH, F, and H2O with cations in [6] coordination only
Group 56 - SOROSILICATES Si2O7 Groups, With Additional O, OH, F and H2O
Si2O7 Groups and O, OH, F, and H2O with cations in [4] coordination
Group 61 - CYCLOSILICATES Six-Membered Rings
Six-Membered Rings with [Si6O18] rings; possible (OH) and Al substitution
Six-Membered Rings with borate groups
Group 71 - PHYLLOSILICATES Sheets of Six-Membered Rings
Sheets of 6-membered rings with 2:1 layers
Group 75 - TECTOSILICATES Si Tetrahedral Frameworks
Si Tetrahedral Frameworks - SiO2 with [4] coordinated Si
Group 76 - TECTOSILICATES Al-Si Framework
Al-Si Framework with Al-Si frameworks
Unclassified Minerals, Mixtures, etc.
var: Aquamarine
var: Smoky Quartz

List of minerals for each chemical element

H TopazAl2(SiO4)(F,OH)2
H BertranditeBe4(Si2O7)(OH)2
H SchorlNa(Fe32+)Al6(Si6O18)(BO3)3(OH)3(OH)
H MuscoviteKAl2(AlSi3O10)(OH)2
Be BerylBe3Al2(Si6O18)
Be BertranditeBe4(Si2O7)(OH)2
Be Beryl (var: Aquamarine)Be3Al2Si6O18
B SchorlNa(Fe32+)Al6(Si6O18)(BO3)3(OH)3(OH)
O BerylBe3Al2(Si6O18)
O QuartzSiO2
O TopazAl2(SiO4)(F,OH)2
O BertranditeBe4(Si2O7)(OH)2
O SchorlNa(Fe32+)Al6(Si6O18)(BO3)3(OH)3(OH)
O Beryl (var: Aquamarine)Be3Al2Si6O18
O AlmandineFe32+Al2(SiO4)3
O MicroclineK(AlSi3O8)
O MuscoviteKAl2(AlSi3O10)(OH)2
O AlbiteNa(AlSi3O8)
O Quartz (var: Smoky Quartz)SiO2
F TopazAl2(SiO4)(F,OH)2
Na SchorlNa(Fe32+)Al6(Si6O18)(BO3)3(OH)3(OH)
Na AlbiteNa(AlSi3O8)
Al BerylBe3Al2(Si6O18)
Al TopazAl2(SiO4)(F,OH)2
Al SchorlNa(Fe32+)Al6(Si6O18)(BO3)3(OH)3(OH)
Al Beryl (var: Aquamarine)Be3Al2Si6O18
Al AlmandineFe32+Al2(SiO4)3
Al MicroclineK(AlSi3O8)
Al MuscoviteKAl2(AlSi3O10)(OH)2
Al AlbiteNa(AlSi3O8)
Si BerylBe3Al2(Si6O18)
Si QuartzSiO2
Si TopazAl2(SiO4)(F,OH)2
Si BertranditeBe4(Si2O7)(OH)2
Si SchorlNa(Fe32+)Al6(Si6O18)(BO3)3(OH)3(OH)
Si Beryl (var: Aquamarine)Be3Al2Si6O18
Si AlmandineFe32+Al2(SiO4)3
Si MicroclineK(AlSi3O8)
Si MuscoviteKAl2(AlSi3O10)(OH)2
Si AlbiteNa(AlSi3O8)
Si Quartz (var: Smoky Quartz)SiO2
S BismuthiniteBi2S3
S MolybdeniteMoS2
K MicroclineK(AlSi3O8)
K MuscoviteKAl2(AlSi3O10)(OH)2
Fe SchorlNa(Fe32+)Al6(Si6O18)(BO3)3(OH)3(OH)
Fe AlmandineFe32+Al2(SiO4)3
Mo MolybdeniteMoS2
Ta Microlite GroupA2-mTa2X6-wZ-n
Bi BismuthiniteBi2S3


Sort by

Year (asc) Year (desc) Author (A-Z) Author (Z-A)
Hall, Frederick. (1840), From the East and from the West. F. Taylor and W. M. Morrison, Washington City.
Stugard, Frederick, Jr. (1958), Pegmatites of the Middletown Area, Connecticut. USGS Bulletin 1042-Q.
Schooner, Richard. (1961), The Mineralogy of Connecticut. Fluorescent House, Branford, Connecticut.
Barton, William R. and Carl E. Goldsmith. (1968), New England Beryllium Investigations. U. S. Bureau of Mines, Report of Investigations 7070.
London, David. (1989), Bedrock Geology of the Moodus Seismic Area, South-Central Connecticut. State Geological and Natural History Survey of Connecticut. Report of Investigations No. 11.
Weber, Marcelle H. and Earle C. Sullivan. (1995), Connecticut Mineral Locality Index. Rocks & Minerals (Connecticut Issue): 70(6): 403.

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