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Timms Hill (Tim's Hill; Iolite Hill), Haddam, Middlesex Co., Connecticut, USAi
Regional Level Types
Timms Hill (Tim's Hill; Iolite Hill)Hill
Haddam- not defined -
Middlesex Co.County
ConnecticutState
USACountry

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Key
Latitude & Longitude (WGS84):
41° 28' 11'' North , 72° 31' 27'' West
Latitude & Longitude (decimal):
Locality type:
Köppen climate type:
Nearest Settlements:
PlacePopulationDistance
Higganum1,698 (2017)4.1km
East Haddam9,042 (2017)5.6km
Moodus1,413 (2017)7.2km
Chester Center1,558 (2017)9.7km
East Hampton2,691 (2017)11.9km


A very coarse-grained vein of oligoclase and smoky quartz similar to the Haddam chrysoberyl locality was uncovered at the top of the east-facing slope on Tim’s Hill in the early 19th century, apparently by "Prof. Mather" (Shepard, 1841). A crude 1845 map of Haddam includes the words "iolite" and "tumalin" near "Tims Hill". According to Davis (1901) it was worked by Nathaniel Cook.

Lacking microcline and conformable to the surrounding gneiss, it is not a true pegmatite. It hosts cordierite (iolite) and was referred to in some old literature as “Iolite Hill”. Shepard (1837) stated that the cordierite “occurs in large massive individuals, having one very eminent cleavage. Its colors are various shades of blue and green, the former predominating...it is transparent in spots, and possessed of dichroism.” Shepard (1841) gives more details and refers to its pseudomorphing mineral (a concept not yet formalized a that time) as "pinite":

The pinite is by far the most abundant variety; good plates of iolite occurring only now and then, in limited areas of a foot or two in diameter, while the pinite is often so abundant, as mechanically to take the place of mica, in the formation of the granite.

The iolite has frequently been procured here in tabular plates, several inches across; and is remarkable for the facility with which it admits of cleavage into still thinner layers. This separation is undoubtedly promoted by the presence of exceedingly thin plates of what seems to be mica. The crystals are but seldom possessed of well defined lateral planes, in consequence of the implantation upon them of mica, albite, tourmaline, and more rarely of tabular spar. When perfect, however, they are either regular hexagonal prisms, or else this form, modified by the replacement of its lateral edges. Their color is a rich dark blue, with an occasional inclination to green; the depth of the color, as is usual in this species, is enhanced by the inspection of the plates in a direction perpendicularly to their cleavage....

The pinite variety, though generally occurring in indeterminate shaped pieces, yet nevertheless is occasionally seen in forms of the same shape and regularity as the iolite, from which, however, it differs essentially in color and hardness. The peculiar tint affected by the pinite is a pale, bluish, chloride green. Its lustre is pearly, and not particularly shining, except in a few specimens, where the color approaches silver-white. Hardness 2.5. Laminae neither flexible nor elastic. Common mica frequently pervades the mineral.


Shepard (1841) noted the similarity of his "pinite" to micaceous "chlorophyllite" from New Hampshire "near J. Neal's mine in Unity". Later writers refer to the fine-grained alteration of cordierite as “fahlunite” and bright green micaceous alteration as “chlorophyllite”. Schorl crystals are also present as “short, doubly terminated black tourmalines (5 to 10 mm. in length).” (Foye (1922)). Williams (circa 1945) states that the “Oligoclase can be had in transparent clear masses.”

The lat. and long. of the primary cordierite locality on Tim's Hill is given below, but other smaller outcrops occur at the top of the slope for 250 meters or more along strike to the north and south. Much anthophyllite can be seen in these outcrops as well.

Regarding bismuthinite, Shepard (1870) reported, "large crystalline masses of bismuthine, more or less coated by bismutite, from a quarryman who had discovered them on the iolite hill...One of the specimens weighs about half a pound; and constitutes a deeply striated or channeled crystal." However, given the lack of further finds, Williams (circa 1945) suggests that the source was really the chrysoberyl locality, where it is well known, and that “the quarryman no doubt did not want to give the right locality.”

Striated magnetites are found at the oligoclase/cordierite rock. The flat-faced, octahedral magnetite crystals come from a chlorite schist at the far south end of the hill, within the power line ROW. This locality has its own page at: http://www.mindat.org/loc-263165.html

Select Mineral List Type

Standard Detailed Strunz Dana Chemical Elements

Mineral List


10 valid minerals.

Detailed Mineral List:

Albite
Formula: Na(AlSi3O8)
Habit: anhedral but in large cleavable masses
Colour: white to pale green
Description: Gemmy and in large cleavable masses.
Reference: Foye, W. G. (1922): Mineral Localities in the Vicinity of Middletown, Connecticut. (American Mineralogist 7:4-12)
Albite var: Oligoclase
Formula: (Na,Ca)[Al(Si,Al)Si2O8]
Habit: anhedral but in large cleavable masses
Colour: white to pale green
Description: Gemmy and in large cleavable masses.
Reference: Foye, W. G. (1922): Mineral Localities in the Vicinity of Middletown, Connecticut. (American Mineralogist 7:4-12)
'Allanite Group' ?
Formula: {A12+REE3+}{M3+2M32+}(Si2O7)(SiO4)O(OH)
Description: Mentioned by Foye (1922) as occurring there, but specimens are lacking.
Reference: Foye, W. G. (1922): Mineral Localities in the Vicinity of Middletown, Connecticut. (American Mineralogist 7:4-12).
Anthophyllite
Formula: ☐{Mg2}{Mg5}(Si8O22)(OH)2
Habit: feathery to acicular prisms
Colour: dark green to green-brown
Description: In radiating sprays of acicular crystals several cm long as layers in light gneiss.
Reference: Lundgren, Lawrence, Jr. (1979), THE BEDROCK GEOLOGY OF THE HADDAM QUADRANGLE. State Geological and Natural History Survey of Connecticut. Quadrangle Report No. 37.
'Biotite'
Formula: K(Fe2+/Mg)2(Al/Fe3+/Mg)([Si/Al]Si2O10)(OH/F)2
Reference: AmMin 7:4
Bismuthinite ?
Formula: Bi2S3
Description: May be erroneous, possibly really from the chrysoberyl locality with similar mineralogy and where it is well-known.
Reference: Rocks & Minerals (1995) 70:396-409
'Chlorophyllite'
Habit: coarse, micaceous pseudomorphs after cordierite
Colour: green
Description: Term used loosely to describe the micaceous mineral of the cordierite pseudomorphs.
Reference: Dana, 1844. A System of Mineralogy, 2nd ed., 306
Cordierite
Formula: (Mg,Fe)2Al3(AlSi5O18)
Habit: pseudohexagonal prism, subhedral blocky to massive
Colour: violet, blue, pale green
Description: Shows good cleavage and typically gemmy, though some of it is altered to dull gray-green "fahlunite". "The iolite has frequently been procured here in tabular plates, several inches across; and is remarkable for the facility with which it admits of cleavage into still thinner layers. This separation is undoubtedly promoted by the presence of exceedingly thin plates of what seems to be mica. The crystals are but seldom possessed of well defined lateral planes, in consequence of the implantation upon them of mica, albite, tourmaline, and more rarely of tabular spar. When perfect, however, they are either regular hexagonal prisms, or else this form, modified by the replacement of its lateral edges. Their color is a rich dark blue, with an occasional inclination to green; the depth of the color, as is usual in this species, is enhanced by the inspection of the plates in a direction perpendicularly to their cleavage." Shepard (1841) "Many beautiful specimens of a clear blue color have been found and cut into gems, showing dichroism by transmitted light. Specimens of this mineral seen in the different collections and museums of this country, you will invariably see labeled from Haddam. The alterations of this mineral are met with here in large quantities." (Davis, 1901).
Reference: Davis, James W. (1901), The Minerals of Haddam, Connecticut Mineral Collector: 8(4): 50-54, and 8(5): 65-70.; Foye, Wilbur G. (1922), Mineral localities in the vicinity of Middletown. American Mineralogist: 7: 4-12.; Shepard, Charles U. (1841), On two Decomposed Varieties of Iolite. American Journal of Science: series 1, 41: 354-358.
'Fahlunite'
Formula: (Mg,Fe)Al2Si3O10 · 2H2O
Habit: pseudomorphs after cordierite
Colour: dull olive green
Description: "The pinite [later fahlunite] variety, though generally occurring in indeterminate shaped pieces, yet nevertheless is occasionally seen in forms of the same shape and regularity as the iolite, from which, however, it differs essentially in color and hardness. The peculiar tint affected by the pinite is a pale, bluish, chloride green. Its lustre is pearly, and not particularly shining, except in a few specimens, where the color approaches silver-white. Hardness 2.5. Laminae neither flexible nor elastic. "in rhombic prisms in great abundance at the Iolite locality, and desirable specimens are easily obtainable. Many of these specimens upon being broken show clear blue Iolite in the interior, from which mineral it, is derived as alteration." (Davis, 1901).
Reference: Davis, James W. (1901): The Minerals of Haddam, Conn. Mineral Collector, v. 8, no. 4, pp. 50-54, and no. 5, pp. 65-70.; Foye, W. G. (1922): Mineral Localities in the Vicinity of Middletown, Connecticut. (American Mineralogist 7:4-12); Shepard, Charles U. (1841): On two Decomposed Varieties of Iolite. American Journal of Science: series 1, 41: 354-358.
Gahnite
Formula: ZnAl2O4
Description: Mentioned by Foye (1922) as occurring there, but specimens are lacking.
Reference: Foye, W. G. (1922): Mineral Localities in the Vicinity of Middletown, Connecticut. (American Mineralogist 7:4-12).
Ilmenite
Formula: Fe2+TiO3
Reference: Rocks & Minerals (1995) 70:396-409
Magnetite
Formula: Fe2+Fe3+2O4
Habit: striated octahedral
Colour: metallic black to gray
Description: Small striated crystals are found in the oligoclase-cordierite vein.
Reference: P. Cristofono collection
Meta-autunite
Formula: Ca(UO2)2(PO4)2 · 6-8H2O
Description: Often coating schorl crystals (Davis, 1901).
Reference: Davis, James W. (1901): The Minerals of Haddam, Conn. Mineral Collector, v. 8, no. 4, pp. 50-54, and no. 5, pp. 65-70.
Quartz
Formula: SiO2
Habit: anhedral
Colour: smoky
Reference: Harold Moritz collection
Quartz var: Smoky Quartz
Formula: SiO2
Habit: anhedral
Colour: smoky
Reference: Harold Moritz collection
Schorl
Formula: Na(Fe2+3)Al6(Si6O18)(BO3)3(OH)3(OH)
Habit: short trigonal prisms, doubly-terminated
Colour: black
Description: "Excellent doubly-terminated crystals of black tourmaline, 1 to 2 inches in length, and 1/2 to 1 inch in diameter are found at the Iolite locality, often covered with incrustation of autunite." (Davis, 1901).
Reference: Davis, James W. (1901): The Minerals of Haddam, Conn. Mineral Collector, v. 8, no. 4, pp. 50-54, and no. 5, pp. 65-70.; Foye, W. G. (1922): Mineral Localities in the Vicinity of Middletown, Connecticut. (American Mineralogist 7:4-12).

List of minerals arranged by Strunz 10th Edition classification

Group 2 - Sulphides and Sulfosalts
Bismuthinite ?2.DB.05Bi2S3
Group 4 - Oxides and Hydroxides
Gahnite4.BB.05ZnAl2O4
Ilmenite4.CB.05Fe2+TiO3
Magnetite4.BB.05Fe2+Fe3+2O4
Quartz4.DA.05SiO2
var: Smoky Quartz4.DA.05SiO2
Group 8 - Phosphates, Arsenates and Vanadates
Meta-autunite8.EB.10Ca(UO2)2(PO4)2 · 6-8H2O
Group 9 - Silicates
Albite9.FA.35Na(AlSi3O8)
var: Oligoclase9.FA.35(Na,Ca)[Al(Si,Al)Si2O8]
Anthophyllite9.DD.05☐{Mg2}{Mg5}(Si8O22)(OH)2
Cordierite9.CJ.10(Mg,Fe)2Al3(AlSi5O18)
Schorl9.CK.05Na(Fe2+3)Al6(Si6O18)(BO3)3(OH)3(OH)
Unclassified Minerals, Rocks, etc.
'Allanite Group' ?-{A12+REE3+}{M3+2M32+}(Si2O7)(SiO4)O(OH)
'Biotite'-K(Fe2+/Mg)2(Al/Fe3+/Mg)([Si/Al]Si2O10)(OH/F)2
'Chlorophyllite'-
'Fahlunite'-(Mg,Fe)Al2Si3O10 · 2H2O

List of minerals arranged by Dana 8th Edition classification

Group 2 - SULFIDES
AmBnXp, with (m+n):p = 2:3
Bismuthinite ?2.11.2.3Bi2S3
Group 4 - SIMPLE OXIDES
A2X3
Ilmenite4.3.5.1Fe2+TiO3
Group 7 - MULTIPLE OXIDES
AB2X4
Gahnite7.2.1.4ZnAl2O4
Magnetite7.2.2.3Fe2+Fe3+2O4
Group 40 - HYDRATED NORMAL PHOSPHATES,ARSENATES AND VANADATES
AB2(XO4)2·xH2O, containing (UO2)2+
Meta-autunite40.2a.1.2Ca(UO2)2(PO4)2 · 6-8H2O
Group 61 - CYCLOSILICATES Six-Membered Rings
Six-Membered Rings with Al substituted rings
Cordierite61.2.1.1(Mg,Fe)2Al3(AlSi5O18)
Six-Membered Rings with borate groups
Schorl61.3.1.10Na(Fe2+3)Al6(Si6O18)(BO3)3(OH)3(OH)
Group 66 - INOSILICATES Double-Width,Unbranched Chains,(W=2)
Amphiboles - Mg-Fe-Mn-Li subgroup
Anthophyllite66.1.2.1☐{Mg2}{Mg5}(Si8O22)(OH)2
Group 75 - TECTOSILICATES Si Tetrahedral Frameworks
Si Tetrahedral Frameworks - SiO2 with [4] coordinated Si
Quartz75.1.3.1SiO2
Group 76 - TECTOSILICATES Al-Si Framework
Al-Si Framework with Al-Si frameworks
Albite76.1.3.1Na(AlSi3O8)
Unclassified Minerals, Mixtures, etc.
var: Oligoclase-(Na,Ca)[Al(Si,Al)Si2O8]
'Allanite Group' ?-{A12+REE3+}{M3+2M32+}(Si2O7)(SiO4)O(OH)
'Biotite'-K(Fe2+/Mg)2(Al/Fe3+/Mg)([Si/Al]Si2O10)(OH/F)2
'Chlorophyllite'-
'Fahlunite'-(Mg,Fe)Al2Si3O10 · 2H2O
Quartz
var: Smoky Quartz
-SiO2

List of minerals for each chemical element

HHydrogen
H SchorlNa(Fe32+)Al6(Si6O18)(BO3)3(OH)3(OH)
H Fahlunite(Mg,Fe)Al2Si3O10 · 2H2O
H Anthophyllite☐{Mg2}{Mg5}(Si8O22)(OH)2
H BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg)([Si/Al]Si2O10)(OH/F)2
H Meta-autuniteCa(UO2)2(PO4)2 · 6-8H2O
H Allanite Group{A12+REE3+}{M23+M32+}(Si2O7)(SiO4)O(OH)
BBoron
B SchorlNa(Fe32+)Al6(Si6O18)(BO3)3(OH)3(OH)
OOxygen
O Albite (var: Oligoclase)(Na,Ca)[Al(Si,Al)Si2O8]
O SchorlNa(Fe32+)Al6(Si6O18)(BO3)3(OH)3(OH)
O Cordierite(Mg,Fe)2Al3(AlSi5O18)
O Fahlunite(Mg,Fe)Al2Si3O10 · 2H2O
O Anthophyllite☐{Mg2}{Mg5}(Si8O22)(OH)2
O AlbiteNa(AlSi3O8)
O BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg)([Si/Al]Si2O10)(OH/F)2
O GahniteZnAl2O4
O MagnetiteFe2+Fe23+O4
O IlmeniteFe2+TiO3
O Meta-autuniteCa(UO2)2(PO4)2 · 6-8H2O
O Quartz (var: Smoky Quartz)SiO2
O QuartzSiO2
O Allanite Group{A12+REE3+}{M23+M32+}(Si2O7)(SiO4)O(OH)
FFluorine
F BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg)([Si/Al]Si2O10)(OH/F)2
NaSodium
Na Albite (var: Oligoclase)(Na,Ca)[Al(Si,Al)Si2O8]
Na SchorlNa(Fe32+)Al6(Si6O18)(BO3)3(OH)3(OH)
Na AlbiteNa(AlSi3O8)
MgMagnesium
Mg Cordierite(Mg,Fe)2Al3(AlSi5O18)
Mg Fahlunite(Mg,Fe)Al2Si3O10 · 2H2O
Mg Anthophyllite☐{Mg2}{Mg5}(Si8O22)(OH)2
Mg BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg)([Si/Al]Si2O10)(OH/F)2
AlAluminium
Al Albite (var: Oligoclase)(Na,Ca)[Al(Si,Al)Si2O8]
Al SchorlNa(Fe32+)Al6(Si6O18)(BO3)3(OH)3(OH)
Al Cordierite(Mg,Fe)2Al3(AlSi5O18)
Al Fahlunite(Mg,Fe)Al2Si3O10 · 2H2O
Al AlbiteNa(AlSi3O8)
Al BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg)([Si/Al]Si2O10)(OH/F)2
Al GahniteZnAl2O4
SiSilicon
Si Albite (var: Oligoclase)(Na,Ca)[Al(Si,Al)Si2O8]
Si SchorlNa(Fe32+)Al6(Si6O18)(BO3)3(OH)3(OH)
Si Cordierite(Mg,Fe)2Al3(AlSi5O18)
Si Fahlunite(Mg,Fe)Al2Si3O10 · 2H2O
Si Anthophyllite☐{Mg2}{Mg5}(Si8O22)(OH)2
Si AlbiteNa(AlSi3O8)
Si BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg)([Si/Al]Si2O10)(OH/F)2
Si Quartz (var: Smoky Quartz)SiO2
Si QuartzSiO2
Si Allanite Group{A12+REE3+}{M23+M32+}(Si2O7)(SiO4)O(OH)
PPhosphorus
P Meta-autuniteCa(UO2)2(PO4)2 · 6-8H2O
SSulfur
S BismuthiniteBi2S3
KPotassium
K BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg)([Si/Al]Si2O10)(OH/F)2
CaCalcium
Ca Albite (var: Oligoclase)(Na,Ca)[Al(Si,Al)Si2O8]
Ca Meta-autuniteCa(UO2)2(PO4)2 · 6-8H2O
TiTitanium
Ti IlmeniteFe2+TiO3
FeIron
Fe SchorlNa(Fe32+)Al6(Si6O18)(BO3)3(OH)3(OH)
Fe Cordierite(Mg,Fe)2Al3(AlSi5O18)
Fe Fahlunite(Mg,Fe)Al2Si3O10 · 2H2O
Fe BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg)([Si/Al]Si2O10)(OH/F)2
Fe MagnetiteFe2+Fe23+O4
Fe IlmeniteFe2+TiO3
ZnZinc
Zn GahniteZnAl2O4
BiBismuth
Bi BismuthiniteBi2S3
UUranium
U Meta-autuniteCa(UO2)2(PO4)2 · 6-8H2O

References

Sort by

Year (asc) Year (desc) Author (A-Z) Author (Z-A)
Shepard, Charles U. (1837), Report On The Geological Survey Of Connecticut. Hamlem, New Haven.
Shepard, Charles U. (1841): On two Decomposed Varieties of Iolite. American Journal of Science: series 1, 41: 354-358.
Map of Haddam (1845), Haddam Historical Society, Thankful Arnold House, Haddam.
Shepard, Charles U. (1870), Mineralogical Contributions, A new variety (species?) of Columbite. American Journal of Science: s. 2, 50: 90.
Davis, James W. (1901), The Minerals of Haddam, Conn. Mineral Collector: 8(4): 50-54 and 8(5): 65-70.
Foye, Wilbur G. (1922), Mineral localities in the vicinity of Middletown. American Mineralogist: 7: 4-12.
Schairer, John F. (1931), Minerals of Connecticut. Connecticut Geological and Natural History Survey Bulletin 51.
Williams, Horace S. (circa 1945), Article For New York Society Of Mineralogists. Brainerd Public Library, Haddam, Connecticut.
Heinrich, E. Wm. (1950), Cordierite in pegmatite near Micanite, Colorado. American Mineralogist: 35: 173-184.
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.
Schooner, Richard. (1961), The Mineralogy of Connecticut. Fluorescent House, Branford, Connecticut.
Lundgren, Lawrence, Jr. (1979), The Bedrock Geology of the Haddam Quadrangle. State Geological and Natural History Survey of Connecticut. Quadrangle Report 37.
Weber, Marcelle H. and Earle C. Sullivan. (1995), Connecticut Mineral Locality Index. Rocks & Minerals (Connecticut Issue): 70(6): 403.

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