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Derby, New Haven Co., Connecticut, USA

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Latitude & Longitude (WGS84): 41° 19' 15'' North , 73° 5' 20'' West
Latitude & Longitude (decimal): 41.32084,-73.08889
GeoHash:G#: drk50f4r3
Köppen climate type:Cfa : Humid subtropical climate

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Select Mineral List Type

Standard Detailed Strunz Dana Chemical Elements

Mineral List

5 valid minerals.

Detailed Mineral List:

Arsenic ?
Formula: As
Reference: Januzzi, 1976. Mineral Localities of CT and Southeastern NY State
Formula: FeAsS
Reference: Januzzi, 1976. Mineral Localities of CT and Southeastern NY State; Samuel Robinson (1825) A Catalogue of American Minerals, with their localities. Boston
'K Feldspar'
Reference: Harvard Mineralogical Museum, no. 108606.
'K Feldspar var: Adularia'
Formula: KAlSi3O8
Reference: Harvard Mineralogical Museum, no. 108606.
Formula: KFe3+4(AsO4)3(OH)4 · 6-7H2O
Reference: Januzzi, 1976. Mineral Localities of CT and Southeastern NY State
Formula: Fe3+AsO4 · 2H2O
Reference: Januzzi, 1976. Mineral Localities of CT and Southeastern NY State
Formula: ☐{Ca2}{Mg5}(Si8O22)(OH)2
Reference: Samuel Robinson (1825) A Catalogue of American Minerals, with their localities. Boston

List of minerals arranged by Strunz 10th Edition classification

Group 1 - Elements
'Arsenic' ?1.CA.05As
Group 2 - Sulphides and Sulfosalts
Group 8 - Phosphates, Arsenates and Vanadates
'Pharmacosiderite'8.DK.10KFe3+4(AsO4)3(OH)4 · 6-7H2O
'Scorodite'8.CD.10Fe3+AsO4 · 2H2O
Group 9 - Silicates
Unclassified Minerals, Rocks, etc.
'K Feldspar'-
'var: Adularia'-KAlSi3O8

List of minerals arranged by Dana 8th Edition classification

Semi-metals and non-metals
Arsenic ?
Group 2 - SULFIDES
AmBnXp, with (m+n):p = 1:2
Scorodite40.4.1.3Fe3+AsO4 · 2H2O
Pharmacosiderite42.8.1a.1KFe3+4(AsO4)3(OH)4 · 6-7H2O
Group 66 - INOSILICATES Double-Width,Unbranched Chains,(W=2)
Amphiboles - Mg-Fe-Mn-Li subgroup
Unclassified Minerals, Rocks, etc.
'K Feldspar'-
'var: Adularia'-KAlSi3O8

List of minerals for each chemical element

H PharmacosideriteKFe43+(AsO4)3(OH)4 · 6-7H2O
H ScoroditeFe3+AsO4 · 2H2O
H Tremolite☐{Ca2}{Mg5}(Si8O22)(OH)2
O K Feldspar (var: Adularia)KAlSi3O8
O PharmacosideriteKFe43+(AsO4)3(OH)4 · 6-7H2O
O ScoroditeFe3+AsO4 · 2H2O
O Tremolite☐{Ca2}{Mg5}(Si8O22)(OH)2
Mg Tremolite☐{Ca2}{Mg5}(Si8O22)(OH)2
Al K Feldspar (var: Adularia)KAlSi3O8
Si K Feldspar (var: Adularia)KAlSi3O8
Si Tremolite☐{Ca2}{Mg5}(Si8O22)(OH)2
S ArsenopyriteFeAsS
K K Feldspar (var: Adularia)KAlSi3O8
K PharmacosideriteKFe43+(AsO4)3(OH)4 · 6-7H2O
Ca Tremolite☐{Ca2}{Mg5}(Si8O22)(OH)2
Fe ArsenopyriteFeAsS
Fe PharmacosideriteKFe43+(AsO4)3(OH)4 · 6-7H2O
Fe ScoroditeFe3+AsO4 · 2H2O
As ArsenicAs
As ArsenopyriteFeAsS
As PharmacosideriteKFe43+(AsO4)3(OH)4 · 6-7H2O
As ScoroditeFe3+AsO4 · 2H2O

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

Ordovician - Neoproterozoic
443.8 - 1000 Ma

ID: 3190671
Precambrian-Phanerozoic sedimentary rocks

Age: Neoproterozoic to Ordovician (443.8 - 1000 Ma)

Lithology: Mudstone-carbonate-sandstone-conglomerate

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: 3011351
Pumpkin Ground Member [of Harrison (Prospect) Gneiss]

Age: Middle Ordovician (458.4 - 470 Ma)

Stratigraphic Name: Harrison Gneiss

Description: Medium- to light-gray, medium- to coarse-grained, well-layered and foliated gneiss, composed of oligoclase, microcline, quartz, and biotite; some layers have numerous microcline megacrysts 1 to 5 cm across; others have hornblende. Minor layers of garnetiferous schist and gneiss. Pumpkin Ground and Beardsley Members of Harrison Gneiss, formerly considered conformable metavolcanic members, are here recognized as juxtaposed metaplutonic units and are renamed the Beardsley and Pumpkin Ground orthogneisses. Isotopic dating yields ages of 428+/-2 Ma (Early Silurian) for the Pumpkin Ground and 446+/-2 Ma (Late Ordovician) for the Beardsley, accepted by authors as crystallization ages. Pumpkin Ground intrudes the Trap Falls Formation. The Harrison Gneiss as described by Rodgers (1985) has no stratigraphic significance and cannot be correlated regionally (Sevigny and Hanson, 1993).

Comments: Part of Central Lowlands; Iapetus (Oceanic) Terrane - Connecticut Valley Synclinorium; Hartland Belt. Secondary unit description per CT007.

Lithology: Major:{gneiss}, Minor:{schist}

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, used under Creative Commons Attribution 4.0 License

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