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Portland, Middlesex Co., Connecticut, USA

Latitude: 41°34'22"N
Longitude: 72°38'28"W
Known as "Quarrytown" primarily for the large "brownstone" quarries (aeolian arkosic sandstone of the Portland Formation) near the Connecticut River in the western part town, Portland is also host to the most famous pegmatite quarry in the area - the Strickland Quarry. Coordinates are for the downtown intersection of State Routes 17A and 66 in the west, which is far removed from the pegmatite quarries farther east.

European settlers arrived in the 1690s, attracted to the blocks of brownstone along the riverbank. Originally Portland was part of Middletown and was known as East Middletown. In 1767 it became the separate town of Chatham. In 1841, when it separated from the eastern part of Chatham, it changed its name first to Conway then to Portland (because of the fame of quarries in that English town) (The remainder of Chatham changed its name to East Hampton in 1915.)

The bedrock geology is split between continental sedimentary rocks in the west, part of the Mesozoic Hartford Basin of the Newark Supergroup and mostly metaplutonic, metavolcanic and metasedimentary metamorphic rocks of the Ordovician Bronson Hill terrane in the east. These terranes are separated by the Eastern Border Fault of the Hartford Basin. Much of the Bronson Hill terrane rocks in town are mixed schists, calc-silicate rocks, and minor quartzites of the Collins Hill Formation, and its metavolcanic member, which are present just east of the Eastern Border Fault. Farther east the bedrock is mostly metaplutonic Glastonbury Gneiss, which crops out as far south as Great Hill Pond. A thin sliver of Devonian Maromas Granite Gneiss is also present.

Portland lies within the Middletown Pegmatite District, and a swarm of Permian pegmatite dikes lies just east of the Eastern Border Fault, mostly within the Collins Hill Formation, but some further east in the Glastonbury Gneiss. These were heavily quarried from the north at the Glastonbury town line and just east of State Route 17 (particularly the long-lived Hale Quarry) southward onto Collins Hill, which hosted the famous Strickland Quarry and Cramer Mine, where most of Portland's diverse mineralogy originates. Most pegmatite specimens just labeled "Portland" are likely from there, although the small Walden Gem Mine and Case Quarries produced many specimens also. Sharply formed and deeply colored aquamarines hail from the small Pelton's Quarry. Unquarried pegmatites can still be easily seen along State Route 66 in the Riverdale section just north of the Connecticut River in the area known as "The Ledges".

Mineral List

Mineral list contains entries from the region specified including sub-localities
Actinolite
Albite
var: Cleavelandite
var: Oligoclase
var: Peristerite
'Allanite'
Almandine
Analcime
Anatase
Anglesite
Annite
Aragonite
Arsenopyrite
Autunite
Bavenite
Bertrandite
Beryl
var: Aquamarine
var: Goshenite
var: Heliodor
var: Morganite
'Biotite'
Bismite
Bismuthinite
Bismutite
Bismutoferrite
Bityite
Calcite
Cassiterite
Chalcopyrite
'Chlorite Group'
Clinozoisite
'Columbite'
Columbite-(Fe)
'Columbite-Tantalite'
Cookeite
Cordierite
Crandallite
Cuprobismutite
Dickinsonite-(KMnNa)
Diopside
Elbaite
Eosphorite
Epidote
Epsomite
'Feldspar Group'
Ferrimolybdite
Fluorapatite
var: Mn-bearing Fluorapatite
Fluorite
Foitite
Gahnite
Galena
'Garnet'
Gobbinsite
Goethite
Graphite
Greenockite
Grossular
'Gummite'
Gypsum
Hematite
Heterosite
Hexahydrite ?
'Hornblende'
Hureaulite
Ilmenite
Ishikawaite
Kaolinite
Kyanite
Lacroixite
Lepidolite
Liandratite
'Limonite'
Lithiophilite
Löllingite
Magnetite
'Manganese Oxides'
'Manganese Oxides
var: Manganese Dendrites'

Melanterite
Meta-autunite
Metatorbernite
Microcline
var: Amazonite
Microlite Group
Mitridatite
Molybdenite
'Monazite'
Monazite-(Ce)
Montebrasite
Montmorillonite
Muscovite
Opal
var: Opal-AN
'Perthite'
Petalite
Phenakite
Phlogopite
Phosphuranylite
Pickeringite
'Pinite'
Pollucite
'Prochlorite'
Purpurite
Pyrite
Pyrochlore Group
Pyrrhotite
Quartz
var: Amethyst
var: Chalcedony
var: Citrine
var: Milky Quartz
var: Rock Crystal
var: Rose Quartz
var: Smoky Quartz
Reddingite
Rhodochrosite
Rutile
Samarskite-(Y)
'Scapolite'
Scheelite
Schorl
Scorodite
Siderite
Sillimanite
Spessartine
Sphalerite
Spodumene
var: Kunzite
Staurolite
Sulphur
Tantalite-(Mn)
'Tapiolite'
Thorogummite
Titanite
Topaz
Torbernite
'Tourmaline'
'var: Indicolite'
'var: Rubellite'
'var: Verdelite'
'var: Watermelon Tourmaline'
Triphylite
Triplite
Uraninite
Uranophane
'Uranpyrochlore (of Hogarth 1977)'
Vivianite
Wodginite
Wollastonite
Xenotime-(Y)
'Zinnwaldite'
Zircon
var: Cyrtolite
Zoisite


191 entries listed. 111 valid minerals.

Localities in this Region

USA
USA

The above list 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

Jarnot, Bruce. (1989): Minerals New to the Portland Area Pegmatites of Central Connecticut. Abstract from the 16th Rochester Mineralogical Symposium April 7, 1989, in Rocks and Minerals, Vol. 64, No. 12, p. 471.

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Copyright © Jolyon Ralph and Ida Chau 1993-2013. Site Map. Locality, mineral & photograph data are the copyright of the individuals who submitted them. Further information contact the Site hosted & developed by Jolyon Ralph. Mindat.org is an online information resource dedicated to providing free mineralogical information to all. Mindat relies on the contributions of hundreds of members and supporters. Mindat does not offer minerals for sale. If you would like to add information to improve the quality of our database, then click here to register.
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