Mineral Evolution Database
Created and maintained by the Mineral Evolution Project in partnership with RRUFF and mindat.
Mineral locality data provided by mindat.org



The Mineral Evolution database is currently under development.

The goal of this page is to present localities at which the mineral is found, and estimates of the oldest possible geologic age of the minerals at these localities.


Locality Name:
Essex Co., Massachusetts, USA

Oldest recorded age at locality: 990
Youngest recorded age at locality: 230.03

mindat Locality ID: 15269
mindat URL: http://www.mindat.org/loc-15269.html

Tectonic Settings:

Total number of sublocalities beneath "Essex Co., Massachusetts, USA": 113
Total number of bottom-level sublocalities: 87

Number of Child Localities: 30
Child Localities:
Amesbury
Andover
Beverly
Boxford
Bradford
Danvers
Essex
Georgetown
Gloucester
Haverhill
Ipswich
Lawrence
Lynn
Lynnfield
Manchester-by-the-Sea (Manchester)
Marblehead
Middleton
Nahant
Newbury
Newburyport
North Andover
Peabody
Rockport
Rowley
Salem
Salisbury
Saugus
Swampscott
Topsfield
West Newbury

Latitude: 42°37'9"N
Longitude: 70°55'21"W
Decimal Degree (lat, lon): 42.619166666667,-70.9225
AThis mineral is Anthropogenic.
GThis mineral is directly dated.
BThis mineral is reported as having this age.
YThis mineral is using an age reported as an element mineralization period.
OThis mineral is using an age calculated from all data at the locality.
RThe age displayed for this mineral originates from a different, non-child locality.
PThe age displayed for this mineral is the range of ages for this mineral at all of this locality's children.
This mineral's age has not yet been recorded.

This Mineral list contains entries from this locality, including sub-localities. Minerals in bold are reported by mindat.org as occurring directly at this locality, and do not occur at any children (sublocalities) of this locality.

Elements at this locality, including sub-localities: Ag Al As Au B Ba Be C Ca Ce Cl Cr Cu F Fe H K Li Mg Mn Mo Na Nb O P Pb S Sb Si Sn Th Ti U Y Zn Zr 

Elements from minerals reported directly at this locality: 

Structural Groups for minerals in this locality: 
AcanthiteAllaniteAmorphousAmphiboleAnalcimeAndalusiteApatiteAragoniteArsenopyriteAstrophyllite
AutuniteBaryteBerylBournoniteBruciteCalciteCancriniteCancrinite-sodaliteChalcopyriteChevkinite
ChloriteChloritoidClayClinozoisiteCopperCorundumCovelliteDiasporeEpidoteFeldspar
FluoriteGadoliniteGarnetKaoliniteLöllingiteMalachiteMarcasiteMicaMolybdeniteNatrolite
NickelineNoneNot in a structural groupOlivinePhenakitePrehnitePyritePyroxeneQuartzRhodonite
RocksaltRutileSapphirineScheeliteSerpentineSodaliteSphaleriteSpinelStibniteSulphur
TalcTetrahedriteTitaniteTourmalineTridymiteVesuvianiteWollastoniteZirconZirconolite

118 IMA Minerals at location:
Acanthite  (*)Actinolite  (*)Aegirine  (*)Aegirine-augite  (*)Aenigmatite  (*)
Albite  (*)Allanite-(Ce)  (*)Almandine  (*)Analcime  (*)Andalusite  (*)
Andradite  (*)Ankerite  (*)Annite  (*)Anorthite  (*)Antigorite  (*)
Arsenopyrite  (*)Astrophyllite  (*)Augite  (*)Autunite  (*)Azurite  (*)
Babingtonite  (*)Baryte  (*)Bertrandite  (*)Beryl  (*)Bornite  (*)
Bournonite  (*)Brucite  (*)Calcite  (*)Cancrinite  (*)Cassiterite  (*)
Cerussite  (*)Chalcopyrite  (*)Chevkinite-(Ce)  (*)Chloritoid  (*)Chromite  (*)
Chrysotile  (*)Clinochlore  (*)Clinozoisite  (*)Covellite  (*)Danalite  (*)
Diadochite  (*)Diopside  (*)Dolomite  (*)Enstatite  (*)Epidote  (*)
Fayalite  (*)Fergusonite-(Y)  (*)Ferrisicklerite  (*)Ferro-anthophyllite  (*)Ferro-hornblende  (*)
Fluorapatite  (*)Fluorite  (*)Galena  (*)Gedrite  (*)Genthelvite  (*)
Goethite  (*)Gold  (*)Graphite  (*)Grossular  (*)Grunerite  (*)
Halite  (*)Hastingsite  (*)Hedenbergite  (*)Hematite  (*)Heterosite  (*)
Hydroxylherderite  (*)Hydrozincite  (*)Ilmenite  (*)Kaolinite  (*)Laumontite  (*)
Lizardite  (*)Löllingite  (*)Magnesite  (*)Magnetite  (*)Malachite  (*)
Marcasite  (*)Microcline  (*)Minnesotaite  (*)Molybdenite  (*)Muscovite  (*)
Natrolite  (*)Nepheline  (*)Opal  (*)Orthoclase  (*)Phenakite  (*)
Phlogopite  (*)Pigeonite  (*)Prehnite  (*)Pyrargyrite  (*)Pyrite  (*)
Pyrrhotite  (*)Quartz  (*)Rhodochrosite  (*)Riebeckite  (*)Rutile  (*)
Sanidine  (*)Schorl  (*)Siderite  (*)Sillimanite  (*)Silver  (*)
Sodalite  (*)Sphalerite  (*)Spinel  (*)Stephanite  (*)Stibnite  (*)
Sulphur  (*)Talc  (*)Tetrahedrite-(Zn)  (*)Thorite  (*)Titanite  (*)
Tremolite  (*)Triphylite  (*)Uranophane-α  (*)Vesuvianite  (*)Wollastonite  (*)
Zircon  (*)Zirconolite  (*)Zoisite  (*)
Mineral nameStructural GroupsIMA FormulaMax Age (Ma)Min Age (Ma)# of Sublocalities containing mineralLOCALITY IDs, not mindat ids# of localities containing mineral
Acanthite  (*)AcanthiteAg2S12193622793
Actinolite  (*)Amphibole   Ca2(Mg4.5-2.5Fe2+0.5-2.5)Si8O22(OH)2503.6350.455219320,219357,219364,219376,2194053419
Aegirine  (*)PyroxeneNaFe3+Si2O6396350.458219304,219306,219315,219320,219323,219324,219353,2193921022
Aegirine-augite  (*)Pyroxene(Ca,Na)(Fe3+,Mg,Fe2+)Si2O63963881219392286
Aenigmatite  (*)SapphirineNa4[Fe2+10Ti2]O4[Si12O36]3963882219392,219395133
Albite  (*)FeldsparNa(AlSi3O8)457335.2614219300,219303,219320,219324,219325,219328,219334,219335,219337,219348,219349,219377,219384,2193948803
Allanite-(Ce)  (*)Allanite EpidoteCaCe(Al2Fe2+)[Si2O7][SiO4]O(OH)1219345706
Almandine  (*)GarnetFe2+3Al2(SiO4)3990230.0312193002353
Analcime  (*)AnalcimeNa(AlSi2O6)·H2O3963882219353,2193921627
Andalusite  (*)AndalusiteAl2SiO5503.6428.274219308,219340,219345,2193571310
Andradite  (*)GarnetCa3Fe3+2(SiO4)312193641534
Ankerite  (*)NoneCa(Fe2+,Mg)(CO3)212193623092
Annite  (*)Mica ClayKFe2+3(AlSi3O10)(OH)2457350.455219324,219335,219336,219384,219392356
Anorthite  (*)FeldsparCa(Al2Si2O8)503.6350.453219320,219357,2193921036
Antigorite  (*)Serpentine ClayMg3Si2O5(OH)43692463219350,219363,219364708
Arsenopyrite  (*)ArsenopyriteFeAsS5219298,219299,219362,219364,2193909052
Astrophyllite  (*)AstrophylliteK2NaFe2+7Ti2(Si4O12)2O2(OH)4F457350.453219320,219324,219387161
Augite  (*)Pyroxene(Ca,Mg,Fe)2Si2O6503.6335.2614219304,219306,219320,219333,219346,219349,219353,219357,219371,219372,219378,219381,219385,2193922060
Autunite  (*)AutuniteCa(UO2)2(PO4)2·10-12H2O990230.0312193021272
Azurite  (*)Not in a structural groupCu3(CO3)2(OH)22219317,2193625509
Babingtonite  (*)RhodoniteCa2Fe2+Fe3+Si5O14(OH)2219313,219378161
Baryte  (*)BaryteBa(SO4)121936211547
Bertrandite  (*)Not in a structural groupBe4Si2O7(OH)2990230.032219302,219377606
Beryl  (*)BerylBe3Al2Si6O18990230.034219300,219302,219303,2193774286
Bornite  (*)NoneCu5FeS43219362,219369,2193705516
Bournonite  (*)BournoniteCuPbSbS312193621089
Brucite  (*)BruciteMg(OH)23692462219350,219364462
Calcite  (*)CalciteCa(CO3)503.6419.8221219301,219313,219317,219320,219323,219328,219356,219357,219359,219363,219364,219365,219369,219372,219376,219378,219384,219389,219403,219405,21940727770
Cancrinite  (*)Cancrinite(Na,Ca,   )8(Al6Si6)O24(CO3,SO4)2·2H2O3963886219304,219353,219354,219392,219395,219397232
Cassiterite  (*)RutileSnO212193045171
Cerussite  (*)AragonitePb(CO3)12193624979
Chalcopyrite  (*)ChalcopyriteCuFeS2503.6428.2711219298,219317,219357,219362,219363,219369,219370,219373,219405,219408,21940927198
Chevkinite-(Ce)  (*)ChevkiniteCe4(Ti,Fe2+,Fe3+)5O8(Si2O7)2364.15350.45121932089
Chloritoid  (*)ChloritoidFe2+Al2O(SiO4)(OH)2364.15350.451219320376
Chromite  (*)SpinelFe2+Cr2O412193633902
Chrysotile  (*)Serpentine ClayMg3Si2O5(OH)43962465219350,219360,219363,219364,219392951
Clinochlore  (*)Chlorite ClayMg5Al(AlSi3O10)(OH)83963882219312,2193921756
Clinozoisite  (*)Clinozoisite EpidoteCa2Al3[Si2O7][SiO4]O(OH)503.6428.272219357,2193761025
Covellite  (*)CovelliteCuS12193624165
Danalite  (*)Cancrinite-sodalite SodaliteBe3Fe2+4(SiO4)3S431.82350.457219320,219324,219334,219335,219384,219387,21938958
Diadochite  (*)AmorphousFe3+2(PO4)(SO4)(OH)·6H2O121930381
Diopside  (*)PyroxeneCaMgSi2O6503.6428.276219304,219357,219363,219364,219370,2193764135
Dolomite  (*)NoneCaMg(CO3)2503.63884219357,219363,219364,2193929895
Enstatite  (*)PyroxeneMg2Si2O63963882219392,219396944
Epidote  (*)Epidote ClinozoisiteCa2(Al2Fe3+)[Si2O7][SiO4]O(OH)503.624610219313,219320,219348,219354,219357,219362,219365,219394,219396,2194058173
Fayalite  (*)OlivineFe2+2(SiO4)4574185219320,219335,219384,219387,219388371
Fergusonite-(Y)  (*)ScheeliteYNbO44574181219384196
Ferrisicklerite  (*)OlivineLi1-x(Fe3+,Mn2+)(PO4)2219303,219377108
Ferro-anthophyllite  (*)Amphibole   Fe2+2Fe2+5Si8O22(OH)2457350.452219320,2193845
Ferro-hornblende  (*)Amphibole   Ca2(Fe2+4Al)(Si7Al)O22(OH)2396350.452219320,219392271
Fluorapatite  (*)ApatiteCa5(PO4)3F990230.033219302,219303,2193772740
Fluorite  (*)FluoriteCaF2503.624614219304,219320,219323,219324,219335,219337,219348,219352,219357,219362,219384,219387,219389,2194059617
Galena  (*)RocksaltPbS503.624624219298,219299,219308,219310,219311,219320,219324,219335,219339,219348,219352,219357,219361,219362,219363,219367,219368,219369,219373,219384,219390,219405,219409,21941024243
Gedrite  (*)Amphibole   Mg2(Mg3Al2)(Si6Al2)O22(OH)2364.15350.451219320178
Genthelvite  (*)Cancrinite-sodalite SodaliteBe3Zn4(SiO4)3S457418121938460
Goethite  (*)DiasporeFeO(OH)2219320,2193357437
Gold  (*)CopperAu383.262464219308,219348,219362,21940730554
Graphite  (*)NoneC383.262465219313,219348,219356,219378,2194072812
Grossular  (*)GarnetCa3Al2(SiO4)3503.6428.273219357,219364,2193761544
Grunerite  (*)Amphibole   Fe2+2Fe2+5Si8O22(OH)2457350.454219320,219324,219384,219387223
Halite  (*)RocksaltNaCl12193221398
Hastingsite  (*)AmphiboleNaCa2(Fe2+4Fe3+)(Si6Al2)O22(OH)2457350.453219304,219320,219384209
Hedenbergite  (*)PyroxeneCaFe2+Si2O6457350.453219320,219384,219388741
Hematite  (*)CorundumFe2O345724612219304,219313,219320,219324,219335,219352,219378,219384,219386,219388,219392,21940514640
Heterosite  (*)OlivineFe3+(PO4)2219303,219377204
Hydroxylherderite  (*)GadoliniteCaBe(PO4)(OH)1219377119
Hydrozincite  (*)NoneZn5(CO3)2(OH)612193621066
Ilmenite  (*)CorundumFe2+Ti4+O3457350.454219300,219303,219320,2193885433
Kaolinite  (*)Clay KaoliniteAl2Si2O5(OH)4364.15350.454219312,219320,219360,2193695591
Laumontite  (*)Not in a structural groupCaAl2Si4O12·4H2O2219356,2194051271
Lizardite  (*)Serpentine ClayMg3Si2O5(OH)4503.6428.271219357359
Löllingite  (*)LöllingiteFeAs21219377762
Magnesite  (*)CalciteMg(CO3)3692464219308,219348,219350,2193601487
Magnetite  (*)SpinelFe2+Fe3+2O4503.624627219301,219304,219306,219320,219323,219324,219325,219328,219330,219346,219348,219349,219350,219353,219354,219357,219372,219381,219384,219385,219387,219388,219389,219392,219395,219405,21940814899
Malachite  (*)MalachiteCu2(CO3)(OH)23219317,219362,21940812537
Marcasite  (*)MarcasiteFeS212193705674
Microcline  (*)FeldsparK(AlSi3O8)457350.4519219302,219304,219305,219306,219320,219323,219324,219325,219328,219330,219334,219335,219337,219353,219384,219388,219392,219394,2194054924
Minnesotaite  (*)Clay TalcFe2+3Si4O10(OH)2457418121938461
Molybdenite  (*)MolybdeniteMoS2431.82350.459219306,219320,219324,219334,219354,219384,219389,219392,2194055800
Muscovite  (*)Mica ClayKAl2(Si3Al)O10(OH)2457230.039219300,219302,219320,219324,219344,219362,219375,219384,21939017380
Natrolite  (*)NatroliteNa2(Si3Al2)O10·2H2O3963882219390,2193921236
Nepheline  (*)TridymiteNa3K(Al4Si4O16)396350.457219304,219306,219320,219353,219354,219392,219396884
Opal  (*)AmorphousSiO2·nH2O396350.459219308,219313,219320,219324,219335,219337,219363,219376,2193922994
Orthoclase  (*)FeldsparK(AlSi3O8)457350.456219304,219320,219354,219384,219392,2193942349
Phenakite  (*)PhenakiteBe2(SiO4)364.15350.451219320326
Phlogopite  (*)Mica ClayKMg3(AlSi3O10)(OH)212193642273
Pigeonite  (*)Pyroxene(Mg,Fe,Ca)2Si2O6503.6350.452219320,219357303
Prehnite  (*)PrehniteCa2Al(Si3Al)O10(OH)2503.6428.275219356,219357,219359,219378,2194051898
Pyrargyrite  (*)NoneAg3SbS312193621425
Pyrite  (*)PyriteFeS2990230.0327219298,219300,219308,219311,219313,219320,219324,219337,219339,219348,219349,219352,219357,219362,219363,219364,219372,219373,219384,219386,219392,219403,219405,219407,219408,219409,21941039462
Pyrrhotite  (*)NickelineFe7S8457350.456219303,219306,219320,219362,219370,2193849056
Quartz  (*)QuartzSiO2990230.0344219300,219302,219303,219304,219306,219307,219308,219311,219313,219320,219323,219324,219325,219328,219330,219334,219335,219337,219346,219348,219349,219356,219357,219362,219363,219364,219365,219369,219371,219372,219375,219376,219378,219381,219384,219386,219387,219388,219389,219390,219400,219403,219405,21940961156
Rhodochrosite  (*)CalciteMn(CO3)12193371711
Riebeckite  (*)Amphibole   Na2(Fe2+3Fe3+2)Si8O22(OH)2396350.456219320,219323,219324,219335,219346,219392375
Rutile  (*)RutileTiO2364.15350.454219324,219337,219372,2194045614
Sanidine  (*)FeldsparK(AlSi3O8)3963882219392,219394598
Schorl  (*)TourmalineNaFe2+3Al6(Si6O18)(BO3)3(OH)3(OH)990230.032219300,2193022705
Siderite  (*)CalciteFe(CO3)383.2624611219320,219324,219334,219335,219337,219348,219362,219363,219364,219369,2194056417
Sillimanite  (*)Not in a structural groupAl2SiO512193751516
Silver  (*)CopperAg12193625186
Sodalite  (*)Cancrinite-sodalite SodaliteNa4(Si3Al3)O12Cl3963886219304,219353,219354,219392,219395,219396444
Sphalerite  (*)SphaleriteZnS364.15350.459219298,219299,219300,219303,219320,219324,219362,219390,21940521482
Spinel  (*)SpinelMgAl2O4503.6428.2712193571934
Stephanite  (*)NoneAg5SbS41219362586
Stibnite  (*)StibniteSb2S312193623418
Sulphur  (*)SulphurS364.15350.4512193242045
Talc  (*)Clay TalcMg3Si4O10(OH)23692463219301,219350,2193713337
Tetrahedrite-(Zn)  (*)TetrahedriteCu6(Cu4Zn2)Sb4S132219317,2193625317
Thorite  (*)ZirconTh(SiO4)431.82350.454219320,219324,219384,2193891006
Titanite  (*)TitaniteCaTi(SiO4)O3963885219304,219320,219333,219364,2193924899
Tremolite  (*)Amphibole   Ca2(Mg5.0-4.5Fe2+0.0-0.5)Si8O22(OH)212194072562
Triphylite  (*)OlivineLiFe2+(PO4)1219303313
Uranophane-α  (*)NoneCa(UO2)2(SiO3OH)2·5H2O990230.031219302890
Vesuvianite  (*)Vesuvianite(Ca,Na)19(Al,Mg,Fe)13(SiO4)10(Si2O7)4(OH,F,O)102219363,2193641395
Wollastonite  (*)WollastoniteCaSiO32219363,2193641247
Zircon  (*)ZirconZr(SiO4)503.6335.2622219304,219320,219323,219324,219325,219328,219330,219335,219346,219349,219353,219357,219372,219381,219384,219387,219388,219389,219392,219394,219395,2194055251
Zirconolite  (*)Zirconolite(Ca,Y)Zr(Ti,Mg,Al)2O74574182219304,219384140
Zoisite  (*)EpidoteCa2Al3[Si2O7][SiO4]O(OH)990230.033219300,219316,2193601025


21 Ages assigned to this locality:

Excel IDMax Age (Ma)Min Age (Ma)Age as listed in referenceDating MethodAge InterpretPrioritized?Sample SourceSample NumRun NumAge from other LocalityDated MineralMinerals explicitely stated as having this ageAge applies to these ElementsMinDat Locality IDDated Locality (Max Age)Location as listed in referenceReferenceReference DOIReference IDAge Notes
USGS-Rb-Sr-06237990918954±36Rb-Sr plagioclase     33585I-93/Dascomb Rd. Area, Andover, Essex Co., Massachusetts, USA USGS-Rb-Sr USGS-Rb-Sr 
USGS-Rb-Sr-06238398382390±8Rb-Sr microcline   Microcline  33585I-93/Dascomb Rd. Area, Andover, Essex Co., Massachusetts, USA USGS-Rb-Sr USGS-Rb-Sr 
USGS-Rb-Sr-06239242.03230.03236.03±6Rb-Sr muscovite   Muscovite  33585I-93/Dascomb Rd. Area, Andover, Essex Co., Massachusetts, USA USGS-Rb-Sr USGS-Rb-Sr 
USGS-Rb-Sr-06241242.03230.03236.03±6Rb-Sr muscovite   Muscovite  33585I-93/Dascomb Rd. Area, Andover, Essex Co., Massachusetts, USA USGS-Rb-Sr USGS-Rb-Sr 
USGS-Rb-Sr-01308350.45350.45350.45Rb-Srinitial age disturbed by weatheringwhole rock     206529Blackburn Circle Locality, Gloucester, Essex Co., Massachusetts, USA USGS-Rb-Sr USGS-Rb-Sr 
USGS-Rb-Sr-01309364.15364.15364.15Rb-Srinitial age disturbed by weatheringwhole rock     206529Blackburn Circle Locality, Gloucester, Essex Co., Massachusetts, USA USGS-Rb-Sr USGS-Rb-Sr 
Alexandra-0417262246254 ± 8K-ArAge of basaltwhole rock     22345Lynnfield, Essex Co., Massachusetts, USALynnfkldZartman et al. (1970)10.1130/0016-7606(1970)81[3359:APDOKR]2.0.CO;2GSAB81_3359 
Alexandra-0418268252260 ± 8K-ArAge of granitebiotite     22345Lynnfield, Essex Co., Massachusetts, USALynnfkldZartman et al. (1970)10.1130/0016-7606(1970)81[3359:APDOKR]2.0.CO;2GSAB81_3359 
Alexandra-0419369349359 ± 10K-ArAge of granitehornblende     22345Lynnfield, Essex Co., Massachusetts, USALynnfkldZartman et al. (1970)10.1130/0016-7606(1970)81[3359:APDOKR]2.0.CO;2GSAB81_3359 
USGS-Rb-Sr-00947383.26335.26359.26±24Rb-Srage of intrusionwhole rock     33588Kallenberg Quarry (Robin Rock Quarry), Lynnfield, Essex Co., Massachusetts, USA USGS-Rb-Sr USGS-Rb-Sr 
USGS-Rb-Sr-00950474.27428.27451.27±23Rb-Srminimum age of intrusionbiotite     22346Nahant, Essex Co., Massachusetts, USA USGS-Rb-Sr USGS-Rb-Sr 
USGS-Rb-Sr-00951503.6461.6482.6±21Rb-Srage of intrusionbiotite     22346Nahant, Essex Co., Massachusetts, USA USGS-Rb-Sr USGS-Rb-Sr 
USGS-Rb-Sr-00934431.82419.82425.82±6Rb-Srage of intrusionwhole rock     47041Babson Farm Quarry, Rockport Granite Company Quarries, Rockport, Essex Co., Massachusetts, USA USGS-Rb-Sr USGS-Rb-Sr 
USGS-Rb-Sr-00935431.82419.82425.82±6Rb-Srage of intrusionwhole rock     47041Babson Farm Quarry, Rockport Granite Company Quarries, Rockport, Essex Co., Massachusetts, USA USGS-Rb-Sr USGS-Rb-Sr 
USGS-U-Th-Pb-00150_206_238426418422±4206_238 zircon   Zircon  47041Babson Farm Quarry, Rockport Granite Company Quarries, Rockport, Essex Co., Massachusetts, USA USGS-U-Th-Pb USGS-U-Th-Pb 
USGS-U-Th-Pb-00150_207_206457445451±6207_206 zircon   Zircon  47041Babson Farm Quarry, Rockport Granite Company Quarries, Rockport, Essex Co., Massachusetts, USA USGS-U-Th-Pb USGS-U-Th-Pb 
USGS-U-Th-Pb-00150_207_235431423427±4207_235 zircon   Zircon  47041Babson Farm Quarry, Rockport Granite Company Quarries, Rockport, Essex Co., Massachusetts, USA USGS-U-Th-Pb USGS-U-Th-Pb 
USGS-Rb-Sr-00936431.82419.82425.82±6Rb-Srage of intrusionwhole rock     209564Flat Ledge Quarry (Flatledge Quarry), Rockport Granite Company Quarries, Rockport, Essex Co., Massachusetts, USA USGS-Rb-Sr USGS-Rb-Sr 
USGS-Rb-Sr-00937431.82419.82425.82±6Rb-Srage of intrusionwhole rock     209564Flat Ledge Quarry (Flatledge Quarry), Rockport Granite Company Quarries, Rockport, Essex Co., Massachusetts, USA USGS-Rb-Sr USGS-Rb-Sr 
USGS-Rb-Sr-00938431.82419.82425.82±6Rb-Srage meaning uncertain (geologic factors)whole rock     209564Flat Ledge Quarry (Flatledge Quarry), Rockport Granite Company Quarries, Rockport, Essex Co., Massachusetts, USA USGS-Rb-Sr USGS-Rb-Sr 
Bradley_2012_072396388392±4U/Pb zircon   Zircon  15757Salem, Essex Co., Massachusetts, USASalem gabbro dioriteMcCauley and Bradley (2014)10.3749/canmin.52.2.183CM52_183 

SampleSource LocalityReference URL
R040092Nahant, Essex Co., Massachusetts, USAhttps://rruff.info/R040092
R080134Rockport, Essex Co., Massachusetts, USAhttps://rruff.info/R080134
FKM-245Salem, Essex Co., Massachusetts, USAhttps://www.rockptx.com/fkm-226-to-fkm-250/#FKM-245

All locality data graciously provided by mindat.org

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