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Gloucester, Essex Co., Massachusetts, USAi
Regional Level Types
Gloucester- not defined -
Essex Co.County
MassachusettsState
USACountry

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Latitude & Longitude (WGS84):
42° 36' 57'' North , 70° 39' 43'' West
Latitude & Longitude (decimal):
Nearest Settlements:
PlacePopulationDistance
Gloucester29,781 (2017)0.0km
Rockport4,966 (2017)5.6km
Manchester-by-the-Sea5,366 (2017)9.7km
Essex1,471 (2017)10.0km
Ipswich4,222 (2017)16.3km


A populated place (city) on Cape Ann.

Area granite quarries and other bedrock exposures. Plutonic rocks of Cape Ann include gabbro, foidal syenite, alkali-feldspar syenite and alkali-feldspar granite. Pegmatites and miarolitic cavities are associated with the granite.

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 from this region.


Mineral List

Mineral list contains entries from the region specified including sub-localities

48 valid minerals.

Detailed Mineral List:

Actinolite
Formula: ☐{Ca2}{Mg4.5-2.5Fe0.5-2.5}(Si8O22)(OH)2
Reference: Gleba, 1978. Massachusetts Mineral & Fossil Localities
Aegirine
Formula: NaFe3+Si2O6
Albite
Formula: Na(AlSi3O8)
Localities: Reported from at least 7 localities in this region.
Reference: Gleba, 1978. Massachusetts Mineral & Fossil Localities
Albite var: Oligoclase
Formula: (Na,Ca)[Al(Si,Al)Si2O8]
Reference: Dennen, W. H. 1992, Bedrock geologic map of the Gloucester and Rockport Quadrangles, Essex County, Massachusetts
'Allanite Group'
Formula: {A12+REE3+}{M3+2M32+}(Si2O7)(SiO4)O(OH)
Reference: Gleba, 1978. Massachusetts Mineral & Fossil Localities
Ankerite ?
Formula: Ca(Fe2+,Mg)(CO3)2
Reference: Gleba, 1978. Massachusetts Mineral & Fossil Localities
Annite
Formula: KFe2+3(AlSi3O10)(OH)2
Anorthite
Formula: Ca(Al2Si2O8)
Reference: Gleba, 1978. Massachusetts Mineral & Fossil Localities
Anorthite var: Labradorite
Formula: (Ca,Na)[Al(Al,Si)Si2O8]
Reference: Sears, John Henry (1905): The Physical Geography, Geology, Mineralogy and Paleontology of Essex County, Massachusetts; Gleba, Peter (1978): Massachusetts Mineral & Fossil Localities.
'Anorthoclase'
Formula: (Na,K)AlSi3O8
Reference: Dennen, W. H. 1992, Bedrock geologic map of the Gloucester and Rockport Quadrangles, Essex County, Massachusetts
'Apatite'
Formula: Ca5(PO4)3(Cl/F/OH)
Reference: Sears, John Henry (1905): The Physical Geography, Geology, Mineralogy and Paleontology of Essex County, Massachusetts
Astrophyllite
Formula: K2NaFe2+7Ti2Si8O28(OH)4F
Reference: Gleba, 1978. Massachusetts Mineral & Fossil Localities
Augite
Formula: (CaxMgyFez)(Mgy1Fez1)Si2O6
'Biotite'
Formula: K(Fe2+/Mg)2(Al/Fe3+/Mg)([Si/Al]Si2O10)(OH/F)2
Reference: Gleba, 1978. Massachusetts Mineral & Fossil Localities
Calcite
Formula: CaCO3
Reference: Gleba, 1978. Massachusetts Mineral & Fossil Localities
Chevkinite-(Ce)
Formula: (Ce,La,Ca,Th)4(Fe2+,Mg)(Fe2+,Ti,Fe3+)2(Ti,Fe3+)2(Si2O7)2O8
Reference: S. Pavadore collection
'Chlorite Group'
Reference: Gleba, 1978. Massachusetts Mineral & Fossil Localities
Chloritoid
Formula: (Fe2+,Mg,Mn2+)Al2(SiO4)O(OH)2
Reference: Gleba, 1978. Massachusetts Mineral & Fossil Localities
'Cryophyllite'
Reference: P. Cristofono collection 2011
Danalite
Formula: Be3Fe2+4(SiO4)3S
Reference: Palache, C. (1907): Phenakite as an Alteration Product of Danalite From Gloucester, Mass. (American Journal of Science 24:252-255); Yale Peabody Museum no. 3290.
Epidote
Formula: {Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH)
Reference: Gleba, 1978. Massachusetts Mineral & Fossil Localities
Fayalite
Formula: Fe2+2SiO4
'Fayalite-Forsterite Series'
Reference: Sears, JH, 1905, Geology of Essex County, Mass
'Feldspar Group'
Reference: Dennen, W. H. 1992, Bedrock geologic map of the Gloucester and Rockport Quadrangles, Essex County, Massachusetts
'Feldspar Group var: Perthite'
Reference: Dennen, W. H. 1992, Bedrock geologic map of the Gloucester and Rockport Quadrangles, Essex County, Massachusetts
'Fergusonite'
Reference: Gleba, 1978. Massachusetts Mineral & Fossil Localities
Ferro-anthophyllite
Formula: ☐{Fe2+2}{Fe2+5}(Si8O22)(OH)2
Reference: Gleba, 1978. Massachusetts Mineral & Fossil Localities
Ferro-hornblende
Formula: ☐{Ca2}{Fe2+4Al}(AlSi7O22)(OH)2
Reference: Dennen, W. H. 1992, Bedrock geologic map of the Gloucester and Rockport Quadrangles, Essex County, Massachusetts
Fluorite
Formula: CaF2
Reference: Gleba, 1978. Massachusetts Mineral & Fossil Localities
Fluorite var: Yttrocerite
Formula: (Ca,Y,Ce)F2+x
Reference: Gleba, 1978. Massachusetts Mineral & Fossil Localities
'Gadolinite'
Reference: Gleba, 1978. Massachusetts Mineral & Fossil Localities
Galena
Formula: PbS
Reference: Gleba, 1978. Massachusetts Mineral & Fossil Localities
Gedrite
Formula: ☐{Mg2}{Mg3Al2}(Al2Si6O22)(OH)2
Reference: Gleba, 1978. Massachusetts Mineral & Fossil Localities
Goethite
Formula: α-Fe3+O(OH)
Reference: Gleba, 1978. Massachusetts Mineral & Fossil Localities
Grunerite
Formula: ☐{Fe2+2}{Fe2+5}(Si8O22)(OH)2
Reference: Gleba, 1978. Massachusetts Mineral & Fossil Localities
Halite
Formula: NaCl
Reference: P Cristofono collection , 2007
Hastingsite
Formula: {Na}{Ca2}{Fe2+4Fe3+}(Al2Si6O22)(OH)2
Reference: AmMin 57:1404-1412 (1972)
Hedenbergite
Formula: CaFe2+Si2O6
Reference: Gleba, 1978. Massachusetts Mineral & Fossil Localities
Hematite
Formula: Fe2O3
'Hornblende'
Reference: Gleba, 1978. Massachusetts Mineral & Fossil Localities
'Hypersthene'
Formula: (Mg,Fe)SiO3
Reference: Sears, JH, 1905, Geology of Essex County, Mass
Ilmenite
Formula: Fe2+TiO3
Reference: Gleba, 1978. Massachusetts Mineral & Fossil Localities
Kaolinite
Formula: Al2(Si2O5)(OH)4
Reference: Gleba, 1978. Massachusetts Mineral & Fossil Localities
'Limonite'
Formula: (Fe,O,OH,H2O)
Reference: Gleba, 1978. Massachusetts Mineral & Fossil Localities
Magnetite
Formula: Fe2+Fe3+2O4
Localities: Reported from at least 6 localities in this region.
Reference: Gleba, 1978. Massachusetts Mineral & Fossil Localities
Microcline
Formula: K(AlSi3O8)
Localities: Reported from at least 9 localities in this region.
Microcline var: Amazonite
Formula: K(AlSi3O8)
Molybdenite
Formula: MoS2
Reference: Gleba, 1978. Massachusetts Mineral & Fossil Localities
'Monazite'
Reference: Dennen, W. H. 1992, Bedrock geologic map of the Gloucester and Rockport Quadrangles, Essex County, Massachusetts
Muscovite
Formula: KAl2(AlSi3O10)(OH)2
Reference: Gleba, 1978. Massachusetts Mineral & Fossil Localities
Nepheline
Formula: Na3K(Al4Si4O16)
Reference: Sears, John Henry (1905): The Physical Geography, Geology, Mineralogy and Paleontology of Essex County, Massachusetts
Opal
Formula: SiO2 · nH2O
Reference: Gleba, 1978. Massachusetts Mineral & Fossil Localities
Opal var: Opal-AN
Formula: SiO2 · nH2O
Reference: Gleba, 1978. Massachusetts Mineral & Fossil Localities
Orthoclase
Formula: K(AlSi3O8)
Reference: Dennen, W. H. 1992, Bedrock geologic map of the Gloucester and Rockport Quadrangles, Essex County, Massachusetts
Phenakite
Formula: Be2SiO4
Reference: Palache, C. (1907): Phenakite as an Alteration Product of Danalite From Gloucester, Mass. (American Journal of Science 24:252-255)
Pigeonite
Formula: (CaxMgyFez)(Mgy1Fez1)Si2O6
Reference: Dennen, W. H. 1992, Bedrock geologic map of the Gloucester and Rockport Quadrangles, Essex County, Massachusetts
'Psilomelane'
Formula: Mn, O
Reference: Gleba, 1978. Massachusetts Mineral & Fossil Localities
Pyrite
Formula: FeS2
Reference: Gleba, 1978. Massachusetts Mineral & Fossil Localities
Pyrrhotite
Formula: Fe7S8
Reference: Gleba, 1978. Massachusetts Mineral & Fossil Localities
Quartz
Formula: SiO2
Localities: Reported from at least 9 localities in this region.
Reference: Gleba, 1978. Massachusetts Mineral & Fossil Localities
Quartz var: Blue Quartz
Formula: SiO2
Reference: Gleba, 1978: MA Mineral and Fossil Localities
Quartz var: Citrine
Formula: SiO2
Reference: Gleba, 1978. Massachusetts Mineral & Fossil Localities
Quartz var: Smoky Quartz
Formula: SiO2
Rhodochrosite
Formula: MnCO3
Reference: Gleba, 1978. Massachusetts Mineral & Fossil Localities
Riebeckite
Formula: ◻[Na2][Fe2+3Fe3+2]Si8O22(OH)2
Reference: Gleba, 1978. Massachusetts Mineral & Fossil Localities
'Riebeckite Root Name'
Formula: ◻[Na2][Z2+3Fe3+2]Si8O22(OH,F,Cl)2
Reference: P Cristofono collection , 2009
'Riebeckite Root Name var: Crocidolite'
Formula: ◻[Na2][Z2+3Fe3+2]Si8O22(OH,F,Cl)2
Reference: P Cristofono collection , 2009
Rutile
Formula: TiO2
Rutile var: Ilmenorutile
Formula: Fex(Nb,Ta)2x · 4Ti1-xO2
Reference: P. Cristofono collection
Siderite
Formula: FeCO3
Reference: Palache, C. (1907): Phenakite as an Alteration Product of Danalite From Gloucester, Mass. (American Journal of Science 24:252-255)
Siderite var: Manganoan Siderite
Formula: (Fe,Mn)CO3
Reference: Palache, Charles (1907): Phenakite as an Alteration Product of Danalite From Gloucester, Mass. (American Journal of Science 24:252-255).
Sphalerite
Formula: ZnS
Reference: Palache, C. (1907): Phenakite as an Alteration Product of Danalite From Gloucester, Mass. (American Journal of Science 24:252-255)
Sulphur
Formula: S8
Colour: yellow
Description: Native sulfur occurs as a rare alteration product of a preexisting mineral, probably sphalerite. Confirmed by SEM-EDS.
Reference: P Cristofono collection 2010
'Tantalite'
Formula: (Mn,Fe)(Ta,Nb)2O6
Reference: Gleba, 1978. Massachusetts Mineral & Fossil Localities
Thorite
Formula: Th(SiO4)
Reference: Gleba, 1978. Massachusetts Mineral & Fossil Localities
Thorite var: Orangite
Formula: Th(SiO4)
Reference: Gleba, 1978. Massachusetts Mineral & Fossil Localities
Titanite
Formula: CaTi(SiO4)O
Reference: Gleba, 1978. Massachusetts Mineral & Fossil Localities
Zircon
Formula: Zr(SiO4)
Localities: Reported from at least 7 localities in this region.
Reference: Gleba, 1978. Massachusetts Mineral & Fossil Localities
Zircon var: Cyrtolite
Formula: Zr[(SiO4),(OH)4]
Reference: Gleba, 1978. Massachusetts Mineral & Fossil Localities

List of minerals arranged by Strunz 10th Edition classification

Group 1 - Elements
Sulphur1.CC.05S8
Group 2 - Sulphides and Sulfosalts
Galena2.CD.10PbS
Molybdenite2.EA.30MoS2
Pyrite2.EB.05aFeS2
Pyrrhotite2.CC.10Fe7S8
Sphalerite2.CB.05aZnS
Group 3 - Halides
Fluorite3.AB.25CaF2
var: Yttrocerite3.AB.25(Ca,Y,Ce)F2+x
Halite3.AA.20NaCl
Group 4 - Oxides and Hydroxides
Goethite4.00.α-Fe3+O(OH)
Hematite4.CB.05Fe2O3
Ilmenite4.CB.05Fe2+TiO3
Magnetite4.BB.05Fe2+Fe3+2O4
Opal4.DA.10SiO2 · nH2O
var: Opal-AN4.DA.10SiO2 · nH2O
Quartz4.DA.05SiO2
var: Blue Quartz4.DA.05SiO2
var: Citrine4.DA.05SiO2
var: Smoky Quartz4.DA.05SiO2
Rutile4.DB.05TiO2
var: Ilmenorutile4.DB.05Fex(Nb,Ta)2x · 4Ti1-xO2
Group 5 - Nitrates and Carbonates
Ankerite ?5.AB.10Ca(Fe2+,Mg)(CO3)2
Calcite5.AB.05CaCO3
Rhodochrosite5.AB.05MnCO3
Siderite5.AB.05FeCO3
var: Manganoan Siderite5.AB.05(Fe,Mn)CO3
Group 9 - Silicates
Actinolite9.DE.10☐{Ca2}{Mg4.5-2.5Fe0.5-2.5}(Si8O22)(OH)2
Aegirine9.DA.25NaFe3+Si2O6
Albite9.FA.35Na(AlSi3O8)
var: Oligoclase9.FA.35(Na,Ca)[Al(Si,Al)Si2O8]
Annite9.EC.20KFe2+3(AlSi3O10)(OH)2
Anorthite9.FA.35Ca(Al2Si2O8)
var: Labradorite9.FA.35(Ca,Na)[Al(Al,Si)Si2O8]
'Anorthoclase'9.FA.30(Na,K)AlSi3O8
Astrophyllite9.DC.05K2NaFe2+7Ti2Si8O28(OH)4F
Augite9.DA.15(CaxMgyFez)(Mgy1Fez1)Si2O6
Chevkinite-(Ce)9.BE.70(Ce,La,Ca,Th)4(Fe2+,Mg)(Fe2+,Ti,Fe3+)2(Ti,Fe3+)2(Si2O7)2O8
Chloritoid9.AF.85(Fe2+,Mg,Mn2+)Al2(SiO4)O(OH)2
Danalite9.FB.10Be3Fe2+4(SiO4)3S
Epidote9.BG.05a{Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH)
Fayalite9.AC.05Fe2+2SiO4
Ferro-anthophyllite9.DD.05☐{Fe2+2}{Fe2+5}(Si8O22)(OH)2
Ferro-hornblende9.DE.10☐{Ca2}{Fe2+4Al}(AlSi7O22)(OH)2
Gedrite9.DD.05☐{Mg2}{Mg3Al2}(Al2Si6O22)(OH)2
Grunerite9.DE.05☐{Fe2+2}{Fe2+5}(Si8O22)(OH)2
Hastingsite9.DE.15{Na}{Ca2}{Fe2+4Fe3+}(Al2Si6O22)(OH)2
Hedenbergite9.DA.15CaFe2+Si2O6
Kaolinite9.ED.05Al2(Si2O5)(OH)4
Microcline9.FA.30K(AlSi3O8)
var: Amazonite9.FA.30K(AlSi3O8)
Muscovite9.EC.15KAl2(AlSi3O10)(OH)2
Nepheline9.FA.05Na3K(Al4Si4O16)
Orthoclase9.FA.30K(AlSi3O8)
Phenakite9.AA.05Be2SiO4
Pigeonite9.DA.10(CaxMgyFez)(Mgy1Fez1)Si2O6
Riebeckite9.DE.25◻[Na2][Fe2+3Fe3+2]Si8O22(OH)2
Thorite9.AD.30Th(SiO4)
var: Orangite9.AD.30Th(SiO4)
Titanite9.AG.15CaTi(SiO4)O
Zircon9.AD.30Zr(SiO4)
var: Cyrtolite9.AD.30Zr[(SiO4),(OH)4]
Unclassified Minerals, Rocks, etc.
'Allanite Group'-{A12+REE3+}{M3+2M32+}(Si2O7)(SiO4)O(OH)
'Apatite'-Ca5(PO4)3(Cl/F/OH)
'Biotite'-K(Fe2+/Mg)2(Al/Fe3+/Mg)([Si/Al]Si2O10)(OH/F)2
'Chlorite Group'-
'Cryophyllite'-
'Fayalite-Forsterite Series'-
'Feldspar Group'-
'var: Perthite'-
'Fergusonite'-
'Gadolinite'-
'Hornblende'-
'Hypersthene'-(Mg,Fe)SiO3
'Limonite'-(Fe,O,OH,H2O)
'Monazite'-
'Psilomelane'-Mn, O
'Riebeckite Root Name'-◻[Na2][Z2+3Fe3+2]Si8O22(OH,F,Cl)2
'var: Crocidolite'-◻[Na2][Z2+3Fe3+2]Si8O22(OH,F,Cl)2
'Tantalite'-(Mn,Fe)(Ta,Nb)2O6

List of minerals arranged by Dana 8th Edition classification

Group 1 - NATIVE ELEMENTS AND ALLOYS
Semi-metals and non-metals
Sulphur1.3.5.1S8
Group 2 - SULFIDES
AmXp, with m:p = 1:1
Galena2.8.1.1PbS
Pyrrhotite2.8.10.1Fe7S8
Sphalerite2.8.2.1ZnS
AmBnXp, with (m+n):p = 1:2
Molybdenite2.12.10.1MoS2
Pyrite2.12.1.1FeS2
Group 4 - SIMPLE OXIDES
A2X3
Hematite4.3.1.2Fe2O3
Ilmenite4.3.5.1Fe2+TiO3
AX2
Rutile4.4.1.1TiO2
var: Ilmenorutile4.4.1.2Fex(Nb,Ta)2x · 4Ti1-xO2
Group 6 - HYDROXIDES AND OXIDES CONTAINING HYDROXYL
XO(OH)
Goethite6.1.1.2α-Fe3+O(OH)
Group 7 - MULTIPLE OXIDES
AB2X4
Magnetite7.2.2.3Fe2+Fe3+2O4
Group 9 - NORMAL HALIDES
AX
Halite9.1.1.1NaCl
AX2
Fluorite9.2.1.1CaF2
Group 14 - ANHYDROUS NORMAL CARBONATES
A(XO3)
Calcite14.1.1.1CaCO3
Rhodochrosite14.1.1.4MnCO3
Siderite14.1.1.3FeCO3
AB(XO3)2
Ankerite ?14.2.1.2Ca(Fe2+,Mg)(CO3)2
Group 51 - NESOSILICATES Insular SiO4 Groups Only
Insular SiO4 Groups Only with cations in [4] coordination
Phenakite51.1.1.1Be2SiO4
Insular SiO4 Groups Only with all cations in octahedral [6] coordination
Fayalite51.3.1.1Fe2+2SiO4
Insular SiO4 Groups Only with cations in >[6] coordination
Thorite51.5.2.3Th(SiO4)
Zircon51.5.2.1Zr(SiO4)
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
Chloritoid52.3.3.1(Fe2+,Mg,Mn2+)Al2(SiO4)O(OH)2
Insular SiO4 Groups and O, OH, F, and H2O with cations in [6] and/or >[6] coordination
Titanite52.4.3.1CaTi(SiO4)O
Group 56 - SOROSILICATES Si2O7 Groups, With Additional O, OH, F and H2O
Si2O7 Groups and O, OH, F, and H2O with cations in [4] and/or >[4] coordination
Chevkinite-(Ce)56.2.8.1(Ce,La,Ca,Th)4(Fe2+,Mg)(Fe2+,Ti,Fe3+)2(Ti,Fe3+)2(Si2O7)2O8
Group 58 - SOROSILICATES Insular, Mixed, Single, and Larger Tetrahedral Groups
Insular, Mixed, Single, and Larger Tetrahedral Groups with cations in [6] and higher coordination; single and double groups (n = 1, 2)
Epidote58.2.1a.7{Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH)
Group 65 - INOSILICATES Single-Width,Unbranched Chains,(W=1)
Single-Width Unbranched Chains, W=1 with chains P=2
Aegirine65.1.3c.2NaFe3+Si2O6
Augite65.1.3a.3(CaxMgyFez)(Mgy1Fez1)Si2O6
Hedenbergite65.1.3a.2CaFe2+Si2O6
Pigeonite65.1.1.4(CaxMgyFez)(Mgy1Fez1)Si2O6
Group 66 - INOSILICATES Double-Width,Unbranched Chains,(W=2)
Amphiboles - Mg-Fe-Mn-Li subgroup
Gedrite66.1.2.5☐{Mg2}{Mg3Al2}(Al2Si6O22)(OH)2
Group 69 - INOSILICATES Chains with Side Branches or Loops
Chains with Side Branches or Loops with (P=2, and N=4, 2 branches)
Astrophyllite69.1.1.1K2NaFe2+7Ti2Si8O28(OH)4F
Group 71 - PHYLLOSILICATES Sheets of Six-Membered Rings
Sheets of 6-membered rings with 2:1 layers
Annite71.2.2b.3KFe2+3(AlSi3O10)(OH)2
Muscovite71.2.2a.1KAl2(AlSi3O10)(OH)2
Group 75 - TECTOSILICATES Si Tetrahedral Frameworks
Si Tetrahedral Frameworks - SiO2 with [4] coordinated Si
Quartz75.1.3.1SiO2
Si Tetrahedral Frameworks - SiO2 with H2O and organics
Opal75.2.1.1SiO2 · nH2O
Group 76 - TECTOSILICATES Al-Si Framework
Al-Si Framework with Al-Si frameworks
Albite76.1.3.1Na(AlSi3O8)
'Anorthoclase'76.1.1.6(Na,K)AlSi3O8
Microcline76.1.1.5K(AlSi3O8)
Orthoclase76.1.1.1K(AlSi3O8)
Al-Si Framework Feldspathoids and related species
Danalite76.2.4.2Be3Fe2+4(SiO4)3S
Nepheline76.2.1.2Na3K(Al4Si4O16)
Unclassified Minerals, Mixtures, etc.
Actinolite-☐{Ca2}{Mg4.5-2.5Fe0.5-2.5}(Si8O22)(OH)2
Albite
var: Oligoclase
-(Na,Ca)[Al(Si,Al)Si2O8]
'Allanite Group'-{A12+REE3+}{M3+2M32+}(Si2O7)(SiO4)O(OH)
Anorthite-Ca(Al2Si2O8)
var: Labradorite-(Ca,Na)[Al(Al,Si)Si2O8]
'Apatite'-Ca5(PO4)3(Cl/F/OH)
'Biotite'-K(Fe2+/Mg)2(Al/Fe3+/Mg)([Si/Al]Si2O10)(OH/F)2
'Chlorite Group'-
'Cryophyllite'-
'Fayalite-Forsterite Series'-
'Feldspar Group'-
'var: Perthite'-
'Fergusonite'-
Ferro-anthophyllite-☐{Fe2+2}{Fe2+5}(Si8O22)(OH)2
Ferro-hornblende-☐{Ca2}{Fe2+4Al}(AlSi7O22)(OH)2
Fluorite
var: Yttrocerite
-(Ca,Y,Ce)F2+x
'Gadolinite'-
Grunerite-☐{Fe2+2}{Fe2+5}(Si8O22)(OH)2
Hastingsite-{Na}{Ca2}{Fe2+4Fe3+}(Al2Si6O22)(OH)2
'Hornblende'-
'Hypersthene'-(Mg,Fe)SiO3
Kaolinite-Al2(Si2O5)(OH)4
'Limonite'-(Fe,O,OH,H2O)
Microcline
var: Amazonite
-K(AlSi3O8)
'Monazite'-
Opal
var: Opal-AN
-SiO2 · nH2O
'Psilomelane'-Mn, O
Quartz
var: Blue Quartz
-SiO2
var: Citrine-SiO2
var: Smoky Quartz-SiO2
Riebeckite-◻[Na2][Fe2+3Fe3+2]Si8O22(OH)2
'Riebeckite Root Name'-◻[Na2][Z2+3Fe3+2]Si8O22(OH,F,Cl)2
'var: Crocidolite'-◻[Na2][Z2+3Fe3+2]Si8O22(OH,F,Cl)2
Siderite
var: Manganoan Siderite
-(Fe,Mn)CO3
'Tantalite'-(Mn,Fe)(Ta,Nb)2O6
Thorite
var: Orangite
-Th(SiO4)
Zircon
var: Cyrtolite
-Zr[(SiO4),(OH)4]

List of minerals for each chemical element

HHydrogen
H Goethiteα-Fe3+O(OH)
H BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg)([Si/Al]Si2O10)(OH/F)2
H Epidote{Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH)
H Riebeckite◻[Na2][Fe32+Fe23+]Si8O22(OH)2
H Limonite(Fe,O,OH,H2O)
H KaoliniteAl2(Si2O5)(OH)4
H MuscoviteKAl2(AlSi3O10)(OH)2
H Opal (var: Opal-AN)SiO2 · nH2O
H Grunerite☐{Fe22+}{Fe52+}(Si8O22)(OH)2
H Actinolite☐{Ca2}{Mg4.5-2.5Fe0.5-2.5}(Si8O22)(OH)2
H AstrophylliteK2NaFe72+Ti2Si8O28(OH)4F
H Allanite Group{A12+REE3+}{M23+M32+}(Si2O7)(SiO4)O(OH)
H Chloritoid(Fe2+,Mg,Mn2+)Al2(SiO4)O(OH)2
H Zircon (var: Cyrtolite)Zr[(SiO4),(OH)4]
H Gedrite☐{Mg2}{Mg3Al2}(Al2Si6O22)(OH)2
H Ferro-anthophyllite☐{Fe22+}{Fe52+}(Si8O22)(OH)2
H ApatiteCa5(PO4)3(Cl/F/OH)
H Hastingsite{Na}{Ca2}{Fe42+Fe3+}(Al2Si6O22)(OH)2
H Ferro-hornblende☐{Ca2}{Fe42+Al}(AlSi7O22)(OH)2
H AnniteKFe32+(AlSi3O10)(OH)2
H Riebeckite Root Name (var: Crocidolite)◻[Na2][Z32+Fe23+]Si8O22(OH,F,Cl)2
H OpalSiO2 · nH2O
H Riebeckite Root Name◻[Na2][Z32+Fe23+]Si8O22(OH,F,Cl)2
BeBeryllium
Be DanaliteBe3Fe42+(SiO4)3S
Be PhenakiteBe2SiO4
CCarbon
C Siderite (var: Manganoan Siderite)(Fe,Mn)CO3
C SideriteFeCO3
C CalciteCaCO3
C RhodochrositeMnCO3
C AnkeriteCa(Fe2+,Mg)(CO3)2
OOxygen
O MicroclineK(AlSi3O8)
O Microcline (var: Amazonite)K(AlSi3O8)
O HematiteFe2O3
O Quartz (var: Smoky Quartz)SiO2
O FayaliteFe22+SiO4
O Siderite (var: Manganoan Siderite)(Fe,Mn)CO3
O TitaniteCaTi(SiO4)O
O MagnetiteFe2+Fe23+O4
O Goethiteα-Fe3+O(OH)
O AlbiteNa(AlSi3O8)
O AnorthiteCa(Al2Si2O8)
O DanaliteBe3Fe42+(SiO4)3S
O BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg)([Si/Al]Si2O10)(OH/F)2
O Epidote{Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH)
O Riebeckite◻[Na2][Fe32+Fe23+]Si8O22(OH)2
O Limonite(Fe,O,OH,H2O)
O SideriteFeCO3
O ZirconZr(SiO4)
O KaoliniteAl2(Si2O5)(OH)4
O MuscoviteKAl2(AlSi3O10)(OH)2
O Opal (var: Opal-AN)SiO2 · nH2O
O Thorite (var: Orangite)Th(SiO4)
O Grunerite☐{Fe22+}{Fe52+}(Si8O22)(OH)2
O Anorthite (var: Labradorite)(Ca,Na)[Al(Al,Si)Si2O8]
O Actinolite☐{Ca2}{Mg4.5-2.5Fe0.5-2.5}(Si8O22)(OH)2
O AstrophylliteK2NaFe72+Ti2Si8O28(OH)4F
O CalciteCaCO3
O HedenbergiteCaFe2+Si2O6
O PhenakiteBe2SiO4
O Allanite Group{A12+REE3+}{M23+M32+}(Si2O7)(SiO4)O(OH)
O Tantalite(Mn,Fe)(Ta,Nb)2O6
O Quartz (var: Citrine)SiO2
O ThoriteTh(SiO4)
O IlmeniteFe2+TiO3
O Chloritoid(Fe2+,Mg,Mn2+)Al2(SiO4)O(OH)2
O Zircon (var: Cyrtolite)Zr[(SiO4),(OH)4]
O Gedrite☐{Mg2}{Mg3Al2}(Al2Si6O22)(OH)2
O QuartzSiO2
O Ferro-anthophyllite☐{Fe22+}{Fe52+}(Si8O22)(OH)2
O PsilomelaneMn, O
O RutileTiO2
O RhodochrositeMnCO3
O AegirineNaFe3+Si2O6
O Augite(CaxMgyFez)(Mgy1Fez1)Si2O6
O Hypersthene(Mg,Fe)SiO3
O ApatiteCa5(PO4)3(Cl/F/OH)
O NephelineNa3K(Al4Si4O16)
O Quartz (var: Blue Quartz)SiO2
O Chevkinite-(Ce)(Ce,La,Ca,Th)4(Fe2+,Mg)(Fe2+,Ti,Fe3+)2(Ti,Fe3+)2(Si2O7)2O8
O Hastingsite{Na}{Ca2}{Fe42+Fe3+}(Al2Si6O22)(OH)2
O Ferro-hornblende☐{Ca2}{Fe42+Al}(AlSi7O22)(OH)2
O OrthoclaseK(AlSi3O8)
O Anorthoclase(Na,K)AlSi3O8
O Pigeonite(CaxMgyFez)(Mgy1Fez1)Si2O6
O Albite (var: Oligoclase)(Na,Ca)[Al(Si,Al)Si2O8]
O AnniteKFe32+(AlSi3O10)(OH)2
O Riebeckite Root Name (var: Crocidolite)◻[Na2][Z32+Fe23+]Si8O22(OH,F,Cl)2
O Rutile (var: Ilmenorutile)Fex(Nb,Ta)2x · 4Ti1-xO2
O OpalSiO2 · nH2O
O Riebeckite Root Name◻[Na2][Z32+Fe23+]Si8O22(OH,F,Cl)2
O AnkeriteCa(Fe2+,Mg)(CO3)2
FFluorine
F FluoriteCaF2
F BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg)([Si/Al]Si2O10)(OH/F)2
F AstrophylliteK2NaFe72+Ti2Si8O28(OH)4F
F Fluorite (var: Yttrocerite)(Ca,Y,Ce)F2+x
F ApatiteCa5(PO4)3(Cl/F/OH)
F Riebeckite Root Name (var: Crocidolite)◻[Na2][Z32+Fe23+]Si8O22(OH,F,Cl)2
F Riebeckite Root Name◻[Na2][Z32+Fe23+]Si8O22(OH,F,Cl)2
NaSodium
Na AlbiteNa(AlSi3O8)
Na Riebeckite◻[Na2][Fe32+Fe23+]Si8O22(OH)2
Na Anorthite (var: Labradorite)(Ca,Na)[Al(Al,Si)Si2O8]
Na AstrophylliteK2NaFe72+Ti2Si8O28(OH)4F
Na AegirineNaFe3+Si2O6
Na NephelineNa3K(Al4Si4O16)
Na Hastingsite{Na}{Ca2}{Fe42+Fe3+}(Al2Si6O22)(OH)2
Na Anorthoclase(Na,K)AlSi3O8
Na Albite (var: Oligoclase)(Na,Ca)[Al(Si,Al)Si2O8]
Na Riebeckite Root Name (var: Crocidolite)◻[Na2][Z32+Fe23+]Si8O22(OH,F,Cl)2
Na HaliteNaCl
Na Riebeckite Root Name◻[Na2][Z32+Fe23+]Si8O22(OH,F,Cl)2
MgMagnesium
Mg BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg)([Si/Al]Si2O10)(OH/F)2
Mg Actinolite☐{Ca2}{Mg4.5-2.5Fe0.5-2.5}(Si8O22)(OH)2
Mg Gedrite☐{Mg2}{Mg3Al2}(Al2Si6O22)(OH)2
Mg Augite(CaxMgyFez)(Mgy1Fez1)Si2O6
Mg Hypersthene(Mg,Fe)SiO3
Mg Chevkinite-(Ce)(Ce,La,Ca,Th)4(Fe2+,Mg)(Fe2+,Ti,Fe3+)2(Ti,Fe3+)2(Si2O7)2O8
Mg Pigeonite(CaxMgyFez)(Mgy1Fez1)Si2O6
Mg AnkeriteCa(Fe2+,Mg)(CO3)2
AlAluminium
Al MicroclineK(AlSi3O8)
Al Microcline (var: Amazonite)K(AlSi3O8)
Al AlbiteNa(AlSi3O8)
Al AnorthiteCa(Al2Si2O8)
Al BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg)([Si/Al]Si2O10)(OH/F)2
Al Epidote{Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH)
Al KaoliniteAl2(Si2O5)(OH)4
Al MuscoviteKAl2(AlSi3O10)(OH)2
Al Anorthite (var: Labradorite)(Ca,Na)[Al(Al,Si)Si2O8]
Al Chloritoid(Fe2+,Mg,Mn2+)Al2(SiO4)O(OH)2
Al Gedrite☐{Mg2}{Mg3Al2}(Al2Si6O22)(OH)2
Al NephelineNa3K(Al4Si4O16)
Al Hastingsite{Na}{Ca2}{Fe42+Fe3+}(Al2Si6O22)(OH)2
Al Ferro-hornblende☐{Ca2}{Fe42+Al}(AlSi7O22)(OH)2
Al OrthoclaseK(AlSi3O8)
Al Anorthoclase(Na,K)AlSi3O8
Al Albite (var: Oligoclase)(Na,Ca)[Al(Si,Al)Si2O8]
Al AnniteKFe32+(AlSi3O10)(OH)2
SiSilicon
Si MicroclineK(AlSi3O8)
Si Microcline (var: Amazonite)K(AlSi3O8)
Si Quartz (var: Smoky Quartz)SiO2
Si FayaliteFe22+SiO4
Si TitaniteCaTi(SiO4)O
Si AlbiteNa(AlSi3O8)
Si AnorthiteCa(Al2Si2O8)
Si DanaliteBe3Fe42+(SiO4)3S
Si BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg)([Si/Al]Si2O10)(OH/F)2
Si Epidote{Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH)
Si Riebeckite◻[Na2][Fe32+Fe23+]Si8O22(OH)2
Si ZirconZr(SiO4)
Si KaoliniteAl2(Si2O5)(OH)4
Si MuscoviteKAl2(AlSi3O10)(OH)2
Si Opal (var: Opal-AN)SiO2 · nH2O
Si Thorite (var: Orangite)Th(SiO4)
Si Grunerite☐{Fe22+}{Fe52+}(Si8O22)(OH)2
Si Anorthite (var: Labradorite)(Ca,Na)[Al(Al,Si)Si2O8]
Si Actinolite☐{Ca2}{Mg4.5-2.5Fe0.5-2.5}(Si8O22)(OH)2
Si AstrophylliteK2NaFe72+Ti2Si8O28(OH)4F
Si HedenbergiteCaFe2+Si2O6
Si PhenakiteBe2SiO4
Si Allanite Group{A12+REE3+}{M23+M32+}(Si2O7)(SiO4)O(OH)
Si Quartz (var: Citrine)SiO2
Si ThoriteTh(SiO4)
Si Chloritoid(Fe2+,Mg,Mn2+)Al2(SiO4)O(OH)2
Si Zircon (var: Cyrtolite)Zr[(SiO4),(OH)4]
Si Gedrite☐{Mg2}{Mg3Al2}(Al2Si6O22)(OH)2
Si QuartzSiO2
Si Ferro-anthophyllite☐{Fe22+}{Fe52+}(Si8O22)(OH)2
Si AegirineNaFe3+Si2O6
Si Augite(CaxMgyFez)(Mgy1Fez1)Si2O6
Si Hypersthene(Mg,Fe)SiO3
Si NephelineNa3K(Al4Si4O16)
Si Quartz (var: Blue Quartz)SiO2
Si Chevkinite-(Ce)(Ce,La,Ca,Th)4(Fe2+,Mg)(Fe2+,Ti,Fe3+)2(Ti,Fe3+)2(Si2O7)2O8
Si Hastingsite{Na}{Ca2}{Fe42+Fe3+}(Al2Si6O22)(OH)2
Si Ferro-hornblende☐{Ca2}{Fe42+Al}(AlSi7O22)(OH)2
Si OrthoclaseK(AlSi3O8)
Si Anorthoclase(Na,K)AlSi3O8
Si Pigeonite(CaxMgyFez)(Mgy1Fez1)Si2O6
Si Albite (var: Oligoclase)(Na,Ca)[Al(Si,Al)Si2O8]
Si AnniteKFe32+(AlSi3O10)(OH)2
Si Riebeckite Root Name (var: Crocidolite)◻[Na2][Z32+Fe23+]Si8O22(OH,F,Cl)2
Si OpalSiO2 · nH2O
Si Riebeckite Root Name◻[Na2][Z32+Fe23+]Si8O22(OH,F,Cl)2
PPhosphorus
P ApatiteCa5(PO4)3(Cl/F/OH)
SSulfur
S PyriteFeS2
S MolybdeniteMoS2
S DanaliteBe3Fe42+(SiO4)3S
S SphaleriteZnS
S GalenaPbS
S PyrrhotiteFe7S8
S SulphurS8
ClChlorine
Cl ApatiteCa5(PO4)3(Cl/F/OH)
Cl Riebeckite Root Name (var: Crocidolite)◻[Na2][Z32+Fe23+]Si8O22(OH,F,Cl)2
Cl HaliteNaCl
Cl Riebeckite Root Name◻[Na2][Z32+Fe23+]Si8O22(OH,F,Cl)2
KPotassium
K MicroclineK(AlSi3O8)
K Microcline (var: Amazonite)K(AlSi3O8)
K BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg)([Si/Al]Si2O10)(OH/F)2
K MuscoviteKAl2(AlSi3O10)(OH)2
K AstrophylliteK2NaFe72+Ti2Si8O28(OH)4F
K NephelineNa3K(Al4Si4O16)
K OrthoclaseK(AlSi3O8)
K Anorthoclase(Na,K)AlSi3O8
K AnniteKFe32+(AlSi3O10)(OH)2
CaCalcium
Ca TitaniteCaTi(SiO4)O
Ca FluoriteCaF2
Ca AnorthiteCa(Al2Si2O8)
Ca Epidote{Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH)
Ca Anorthite (var: Labradorite)(Ca,Na)[Al(Al,Si)Si2O8]
Ca Actinolite☐{Ca2}{Mg4.5-2.5Fe0.5-2.5}(Si8O22)(OH)2
Ca CalciteCaCO3
Ca HedenbergiteCaFe2+Si2O6
Ca Fluorite (var: Yttrocerite)(Ca,Y,Ce)F2+x
Ca Augite(CaxMgyFez)(Mgy1Fez1)Si2O6
Ca ApatiteCa5(PO4)3(Cl/F/OH)
Ca Chevkinite-(Ce)(Ce,La,Ca,Th)4(Fe2+,Mg)(Fe2+,Ti,Fe3+)2(Ti,Fe3+)2(Si2O7)2O8
Ca Hastingsite{Na}{Ca2}{Fe42+Fe3+}(Al2Si6O22)(OH)2
Ca Ferro-hornblende☐{Ca2}{Fe42+Al}(AlSi7O22)(OH)2
Ca Pigeonite(CaxMgyFez)(Mgy1Fez1)Si2O6
Ca Albite (var: Oligoclase)(Na,Ca)[Al(Si,Al)Si2O8]
Ca AnkeriteCa(Fe2+,Mg)(CO3)2
TiTitanium
Ti TitaniteCaTi(SiO4)O
Ti AstrophylliteK2NaFe72+Ti2Si8O28(OH)4F
Ti IlmeniteFe2+TiO3
Ti RutileTiO2
Ti Chevkinite-(Ce)(Ce,La,Ca,Th)4(Fe2+,Mg)(Fe2+,Ti,Fe3+)2(Ti,Fe3+)2(Si2O7)2O8
Ti Rutile (var: Ilmenorutile)Fex(Nb,Ta)2x · 4Ti1-xO2
MnManganese
Mn Siderite (var: Manganoan Siderite)(Fe,Mn)CO3
Mn Tantalite(Mn,Fe)(Ta,Nb)2O6
Mn PsilomelaneMn, O
Mn RhodochrositeMnCO3
FeIron
Fe HematiteFe2O3
Fe FayaliteFe22+SiO4
Fe Siderite (var: Manganoan Siderite)(Fe,Mn)CO3
Fe PyriteFeS2
Fe MagnetiteFe2+Fe23+O4
Fe Goethiteα-Fe3+O(OH)
Fe DanaliteBe3Fe42+(SiO4)3S
Fe BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg)([Si/Al]Si2O10)(OH/F)2
Fe Epidote{Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH)
Fe Riebeckite◻[Na2][Fe32+Fe23+]Si8O22(OH)2
Fe Limonite(Fe,O,OH,H2O)
Fe SideriteFeCO3
Fe Grunerite☐{Fe22+}{Fe52+}(Si8O22)(OH)2
Fe Actinolite☐{Ca2}{Mg4.5-2.5Fe0.5-2.5}(Si8O22)(OH)2
Fe AstrophylliteK2NaFe72+Ti2Si8O28(OH)4F
Fe HedenbergiteCaFe2+Si2O6
Fe PyrrhotiteFe7S8
Fe Tantalite(Mn,Fe)(Ta,Nb)2O6
Fe IlmeniteFe2+TiO3
Fe Chloritoid(Fe2+,Mg,Mn2+)Al2(SiO4)O(OH)2
Fe Ferro-anthophyllite☐{Fe22+}{Fe52+}(Si8O22)(OH)2
Fe AegirineNaFe3+Si2O6
Fe Augite(CaxMgyFez)(Mgy1Fez1)Si2O6
Fe Hypersthene(Mg,Fe)SiO3
Fe Chevkinite-(Ce)(Ce,La,Ca,Th)4(Fe2+,Mg)(Fe2+,Ti,Fe3+)2(Ti,Fe3+)2(Si2O7)2O8
Fe Hastingsite{Na}{Ca2}{Fe42+Fe3+}(Al2Si6O22)(OH)2
Fe Ferro-hornblende☐{Ca2}{Fe42+Al}(AlSi7O22)(OH)2
Fe Pigeonite(CaxMgyFez)(Mgy1Fez1)Si2O6
Fe AnniteKFe32+(AlSi3O10)(OH)2
Fe Riebeckite Root Name (var: Crocidolite)◻[Na2][Z32+Fe23+]Si8O22(OH,F,Cl)2
Fe Rutile (var: Ilmenorutile)Fex(Nb,Ta)2x · 4Ti1-xO2
Fe Riebeckite Root Name◻[Na2][Z32+Fe23+]Si8O22(OH,F,Cl)2
Fe AnkeriteCa(Fe2+,Mg)(CO3)2
ZnZinc
Zn SphaleriteZnS
YYttrium
Y Fluorite (var: Yttrocerite)(Ca,Y,Ce)F2+x
ZrZirconium
Zr ZirconZr(SiO4)
Zr Zircon (var: Cyrtolite)Zr[(SiO4),(OH)4]
NbNiobium
Nb Tantalite(Mn,Fe)(Ta,Nb)2O6
Nb Rutile (var: Ilmenorutile)Fex(Nb,Ta)2x · 4Ti1-xO2
MoMolybdenum
Mo MolybdeniteMoS2
LaLanthanum
La Chevkinite-(Ce)(Ce,La,Ca,Th)4(Fe2+,Mg)(Fe2+,Ti,Fe3+)2(Ti,Fe3+)2(Si2O7)2O8
CeCerium
Ce Fluorite (var: Yttrocerite)(Ca,Y,Ce)F2+x
Ce Chevkinite-(Ce)(Ce,La,Ca,Th)4(Fe2+,Mg)(Fe2+,Ti,Fe3+)2(Ti,Fe3+)2(Si2O7)2O8
TaTantalum
Ta Tantalite(Mn,Fe)(Ta,Nb)2O6
Ta Rutile (var: Ilmenorutile)Fex(Nb,Ta)2x · 4Ti1-xO2
PbLead
Pb GalenaPbS
ThThorium
Th Thorite (var: Orangite)Th(SiO4)
Th ThoriteTh(SiO4)
Th Chevkinite-(Ce)(Ce,La,Ca,Th)4(Fe2+,Mg)(Fe2+,Ti,Fe3+)2(Ti,Fe3+)2(Si2O7)2O8

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

Paleozoic
251.902 - 541 Ma



ID: 3191988
Paleozoic intrusive rocks

Age: Phanerozoic (251.902 - 541 Ma)

Lithology: Intrusive igneous rocks

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]

Wenlock - Late Ordovician
427.4 - 458.4 Ma



ID: 2742559
Cape Ann Complex

Age: Paleozoic (427.4 - 458.4 Ma)

Stratigraphic Name: Cape Ann Complex

Description: Alkalic granite to quartz syenite containing ferro-hornblende. Intrudes Zdigb. Most of Cape Ann Complex forms Cape Ann peninsula of northeastern MA. Consists of alkalic granite to quartz syenite (its main phase), Beverly Syenite, and Squam Granite, all of which form a pluton covering 385 sq km. Intrudes Late Proterozoic greenschist, diorite, and gabbro that earlier workers assigned to Marlboro Formation, Salem Gabbro-Diorite, or Middlesex Fells Volcanic Complex. Dennen (1975) considered masses of diorite and gabbro within and adjacent to Cape Ann Complex to be cogenetic with it and equivalent in age to Nahant Gabbro and gabbro at Salem Neck. Authors recommend that usage of term Salem Gabbro-Diorite be restricted to these masses of diorite and gabbro in and around Cape Ann pluton that are younger than Dedham Granite and cogenetic with Cape Ann Complex. Gabbro at Salem Neck is probably representative. Radiometric ages straddle Late Ordovician-Early Silurian boundary. Age is based on Rb-Sr whole rock isochron of 426 +/-6 Ma (Zartman and Marvin, 1971) and U-Pb zircon date of 450 +/-25 Ma (Zartman, 1977) (Wones and Goldsmith, 1991).

Comments: Part of Milford-Dedham Zone (Tertiary and Older Rocks). Secondary unit description per MA007. Original map source: Unpublished Digital Geologic Map of Massachusetts received from Rudi Hon of Boston College in 1998; based on the 1983 USGS paper version (MA002).

Lithology: Major:{alkali granite,quartz syenite}

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]

Ordovician
443.8 - 485.4 Ma



ID: 2702709
Cape Ann Granite, alkali-feldspar granite

Age: Ordovician (443.8 - 485.4 Ma)

Stratigraphic Name: Cape Ann Granite

Description: Modal quartz content greater than 25 percent

Comments: The principal rock of the map area is the Cape Ann Granite, an unfoliated, medium- to coarse-grained, leucocratic rock ranging in composition from quartzose alkali-feldspar granite, through alkali-feldspar quartz syenite, to alkali-feldspar syenite. Its texture is generally uneven, subhedral to subporphyritic, and locally cumulus. Crystals range from 0.5 to 1 cm (0.2 to 0.4 in.) long in the quartz-bearing rocks and are less uniform in the syenitic rocks. Most of the syenite is texturally equivalent to the granite, but the syenite commonly contains small, irregular pegmatitic patches that lack well-defined boundaries. The range (and median) of the principal minerals are: potassium feldspar, 53-85 (63) percent; plagioclase (An6-12), 0-22.5 (2.8) percent; quartz, 0-41 (24) percent; ferrohornblende, 0.1-17 (4.5) percent; biotite, 0-3.2 (0.8) percent; and opaque minerals, 0.2-7.5 (1.0) percent. Minor quantities of augite are in approximately one-quarter of the specimens. Accessory minerals include magnetite, ilmenite, zircon, apatite, and, very rarely, fluorite, pyrite or molybdenite. Carlsbad-twinned microcline microperthite is the dominant feldspar; less than 25 percent of the feldspar is homogeneous microcline. Plagioclase (albite or oligoclase) is present in only minor quantities. Quartz is clear, grayish, pinkish, or faintly smoky, shows weak strain shadows, and contains oriented sheets of dust-like inclusions and vesicles. Potassium feldspar and quartz occur as large single crystals and as clusters of subhedral to euhedral feldspar and anhedral quartz partly to completely surrounded by finer grained quartz and feldspar. The mafic minerals are variable in amount and appearance and occur as ragged clots, wisps, single subhedral crystals, and zoned reaction aggregates. Augite is colorless to pale green, typically occurring as a core that is partly or completely surrounded by pale-green amphibole, darker green sodium-iron amphibole, and reddish-brown biotite; magnetite granules are scattered throughout the aggregate. Sodium-iron amphibole and biotite occur as both isolated crystals and clots of both minerals. The mapped lithotypes of the Cape Ann Granite were determined by modal quartz content, because the amount of quartz in these subunits is consistent and varies smoothly in areas generally measurable in square kilometers (miles). Arbitrary divisions of 5, 15, and 25 volume percent of quartz were determined by point counts on outcrops. These lithotypes form irregular northeast-bending bands. Neither stratigraphic succession nor dips of these lithotypes is known, but field relations suggest the superposition of quartz-rich on quartz-poor types. The lithotypes probably originated by differential crystal settling, but may have had their origin in convective motions of the magma. Weathering causes sequential color changes in these felsic rocks from dark green to green gray or gray, then to brown, tan, and finally to white on exposed surfaces. The weathered surface is black-brown and grus is common under vegetation. Joints are commonly bordered by a brown zone a few centimeters (inches) thick. Xenoliths, which are generally small and well digested, but locally may retain their preincorporation character, are scattered throughout the intrusion. They include blocks of a fine-grained granite, probably the Squam Granite; Salem Gabbro-diorite and other fine-grained, commonly porphyritic mafic rocks; and siliceous metasedimentary rocks. Many of these latter were originally finely laminated (0.1 to 5 mm (0.004-0.2 in.)), but have been transformed by thermal metamorphism into thin-banded quartz-biotite rocks containing feldspars and hornblende. A few of these metasedimentary xenoliths contain muscovite, pyroxene, and garnet; one sample contains sillimanite.

Reference: Dennen, W.H. Bedrock geologic map of the Gloucester and Rockport quadrangles, Massachusetts. U.S. Geological Survey Miscellaneous Investigations Series Map I-2285. Digital Conversion 2007. [130]

Data and map coding provided by Macrostrat.org, used under Creative Commons Attribution 4.0 License

References

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Year (asc) Year (desc) Author (A-Z) Author (Z-A)
Cooke, Josiah P., Jr. (1866): On Danalite, a new Mineral Species from the Granite of Rockport, Mass. (American Journal of Science and Arts 47:73-78).
Shaler, N. S. (1888): The Geology of Cape Ann, Massachusetts. (U. S. Geological Survey Ninth Annual Report)
Sears, John Henry (1905): The Physical Geography, Geology, Mineralogy and Paleontology of Essex County.
Palache, Charles (1907): Phenacite as an Alteration Product of Danalite from Gloucester, Mass. (American Journal of Science 24:252-255).
Dennen, W. H. (1992): Bedrock geologic map of the Gloucester and Rockport Quadrangles, Essex County, Massachusetts.

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