archean

Metamorphosed pillow basalt (Ely Greenstone, Neoarchean, ~2.722 Ga; large glacial erratic along Main Street, Ely, Minnesota, USA) 15
by James St. John

Red quartz crystals lining void in specularite (Soudan Iron-Formation, Neoarchean, 2.722 Ga; Montana Stope, 27th level of the Soudan Mine, Soudan, Minnesota, USA) 3
by James St. John

Gneiss (Archean; Windy Lake Northwest roadcut, Sudbury Impact Structure, Ontario, Canada) 4
by James St. John

Fault with fault breccia in interbedded metagraywacke-slate (Lake Vermilion Formation, Neoarchean, 2.695-2.722 Ga; Pike River Bridge outcrop, just north of Peyla, Minnesota, USA) 12
by James St. John

Metamorphosed pillow basalt (Ely Greenstone, Neoarchean, ~2.722 Ga; large glacial erratic along Main Street, Ely, Minnesota, USA) 5
by James St. John

Lamprophyre with xenolith (Dubreuilville Dike, Archean; Route 17 roadcut southeast of Princess Lake & north of Wawa, Ontario, Canada) 26
by James St. John

Sulfidic basaltic lapillistone (Middle Tholeiitic Unit, Kidd-Munro Assemblage, Neoarchean, 2.711 to 2.719 Ga; drill core at the Potter Mine, east of Timmins, Ontario, Canada) 2
by James St. John

Metamorphosed pillow basalt (Ely Greenstone, Neoarchean, ~2.722 Ga; large glacial erratic along Main Street, Ely, Minnesota, USA) 8
by James St. John

Staurolite schist (Keivy Schist; Mt. Ploskaya, Kola Peninsula, Russia) 12
by James St. John

Bismuthinite & molybdenite in pegmatitic granite (Preissac-Lacorne Batholith, Neoarchean, 2.630-2.675 Ga; Moly Hill, Quebec, Canada) 2
by James St. John

Metamorphosed pillow basalt (Ely Greenstone, Neoarchean, ~2.722 Ga; large glacial erratic along Main Street, Ely, Minnesota, USA) 25
by James St. John

Banded iron formation (Negaunee Iron-Formation, Paleoproterozoic, 1.874 or 2.11 Ga; Cliffs Shaft Mine, Ishpeming, Michigan, USA) 1
by James St. John

Lamprophyre with xenoliths (Dubreuilville Dike, Archean; Route 17 roadcut southeast of Princess Lake & north of Wawa, Ontario, Canada) 121
by James St. John

Hematite-rich iron ore (Precambrian; Pioneer Mine, Ely, Minnesota, USA) 2
by James St. John

Vesicular metakomatiite (serpentinized) (Upper Komatiitic Unit, Kidd-Munro Assemblage, Neoarchean, 2.711-2.717 Ga; west-southwest of the Potter Mine, east of Timmins, Ontario, Canada) 6
by James St. John

Interbedded metagraywacke-slate (Lake Vermilion Formation, Neoarchean, 2.695-2.722 Ga; Pike River Bridge outcrop, just north of Peyla, Minnesota, USA) 14
by James St. John

Metamorphosed pillow basalt (Ely Greenstone, Neoarchean, ~2.722 Ga; large glacial erratic along Main Street, Ely, Minnesota, USA) 7
by James St. John

Garnetite (alteration halo around magnetite-rich meta-iron formation) (Archean, metamorphism at ~3.2 Ga & ~2.8 Ga; Quad Creek section - roadcut along the Beartooth Highway, Beartooth Mountains, Montana, USA) 6
by James St. John

Polymetallic massive sulfide (Middle Tholeiitic Unit, Kidd-Munro Assemblage, Neoarchean, 2.711 to 2.719 Ga; Potter Mine, east of Timmins, Ontario, Canada) 3
by James St. John

Interbedded metagraywacke-slate with silicified joints (Lake Vermilion Formation, Neoarchean, 2.695-2.722 Ga; Pike River Bridge outcrop, just north of Peyla, Minnesota, USA) 8
by James St. John

Fuchsitic quartzite (Elmers Rock Greenstone Belt, Archean, >2.54 Ga; Laramie Range, Wyoming, USA) 35
by James St. John

Spinifex komatiite sill in cumulate komatiite lava flow (Upper Komatiitic Unit, Kidd-Munro Assemblage, Neoarchean, 2.711-2.717 Ga; Pyke Hill, near the Potter Mine, east of Timmins, Ontario, Canada) 37
by James St. John

Spinifex komatiite sills in cumulate komatiite lava flow (Upper Komatiitic Unit, Kidd-Munro Assemblage, Neoarchean, 2.711-2.717 Ga; Pyke Hill, near the Potter Mine, east of Timmins, Ontario, Canada) 2
by James St. John

Lamprophyre with xenoliths (Dubreuilville Dike, Archean; Route 17 roadcut southeast of Princess Lake & north of Wawa, Ontario, Canada) 123
by James St. John

Exploration drill cores (Potter Mine, east of Timmins, Ontario, Canada)
by James St. John

Fault with fault breccia in interbedded metagraywacke-slate (Lake Vermilion Formation, Neoarchean, 2.695-2.722 Ga; Pike River Bridge outcrop, just north of Peyla, Minnesota, USA) 2
by James St. John

Fuchsitic quartzite (Elmers Rock Greenstone Belt, Archean, >2.54 Ga; Laramie Range, Wyoming, USA) 40
by James St. John

Interbedded specularite-quartzite (meta-BIF) (Negaunee Iron-Formation, Paleoproterozoic, 1.874 or 2.11 Ga; Republic Mine, Marquette County, Upper Peninsula of Michigan, USA) 1
by James St. John

Magnetite-rich banded iron-formation (BIF) (Michipicoten Iron-Formation, Neoarchean, 2696-2749 Ma; outcrop above Route 17 roadcut east of Bridget Lake, south of Wawa, Ontario, Canada) 197
by James St. John

End-Pleistocene large pothole in tholeiitic basalt (Clam Falls Volcanics, Mesoproterozoic, ~1.1 Ga; Interstate State Park, Taylors Falls, Minnesota, USA) 5
by James St. John

Metamorphosed pillow basalt (Ely Greenstone, Neoarchean, ~2.722 Ga; Rt. 169 roadcut just east of Ely, Minnesota, USA) 1
by James St. John

Red quartz crystals lining void in specularite (Soudan Iron-Formation, Neoarchean, 2.722 Ga; Montana Stope, 27th level of the Soudan Mine, Soudan, Minnesota, USA) 1
by James St. John

Red quartz crystals lining void in specularite (Soudan Iron-Formation, Neoarchean, 2.722 Ga; Montana Stope, 27th level of the Soudan Mine, Soudan, Minnesota, USA) 6
by James St. John

Isoclinal fold in gneiss (Archean; Ennis Lake North roadcut, Madison County, Montana, USA) 3
by James St. John

Metakomatiite lava flows (Upper Komatiitic Unit, Kidd-Munro Assemblage, Neoarchean, 2.711-2.719 Ga; Pyke Hill, near the Potter Mine, east of Timmins, Ontario, Canada) 24
by James St. John

Sulfidic basaltic lapillistone (Middle Tholeiitic Unit, Kidd-Munro Assemblage, Neoarchean, 2.711 to 2.719 Ga; drill core at the Potter Mine, east of Timmins, Ontario, Canada) 3
by James St. John

Soapstone (late Mesoproterozoic, 1.1-1.3 Ga; Regal Mine, Ruby Range, Montana, USA) 8
by James St. John

Magnetite banded iron formation (Soudan Iron-Formation, Neoarchean, ~2.722 Ga; Rt. 169 roadcut between Soudan & Robinson, Minnesota, USA) 5
by James St. John

Quartz (hosted in Soudan Iron-Formation, Neoarchean, ~2.722 Ga; iron mine in Soudan, Minnesota, USA) 2
by James St. John

Spinifex metakomatiite (Upper Komatiitic Unit, Kidd-Munro Assemblage, Neoarchean, 2.711-2.719 Ga; Pyke Hill, near the Potter Mine, east of Timmins, Ontario, Canada) 17
by James St. John

Chromitic dunite (Stillwater Complex, Neoarchean, 2.71 Ga; Beartooth Mountains, Montana, USA) 4
by James St. John

Red quartz crystals lining void in specularite (Soudan Iron-Formation, Neoarchean, 2.722 Ga; Montana Stope, 27th level of the Soudan Mine, Soudan, Minnesota, USA) 5
by James St. John

Columnar-jointed komatiite lava flow (Upper Komatiitic Unit, Kidd-Munro Assemblage, Neoarchean, 2.711-2.717 Ga; southwest of the Potter Mine, east of Timmins, Ontario, Canada) 3
by James St. John

Spinifex metakomatiite (Upper Komatiitic Unit, Kidd-Munro Assemblage, Neoarchean, 2.711-2.719 Ga; Pyke Hill, near the Potter Mine, east of Timmins, Ontario, Canada) 10
by James St. John

Chlorite schist (Neoarchean; Soudan Mine, Soudan, Minnesota, USA) 3
by James St. John

Jaspilite banded iron formation (Soudan Iron-Formation, Neoarchean, ~2.722 Ga; Stuntz Bay Road outcrop, Soudan Underground State Park, Soudan, Minnesota, USA) 38
by James St. John

Jaspilite banded iron formation (Soudan Iron-Formation, Neoarchean, ~2.722 Ga; Stuntz Bay Road outcrop, Soudan Underground State Park, Soudan, Minnesota, USA) 42
by James St. John

Sulfidic basaltic lapillistone (Middle Tholeiitic Unit, Kidd-Munro Assemblage, Neoarchean, 2.711 to 2.719 Ga; drill core at the Potter Mine, east of Timmins, Ontario, Canada) 9
by James St. John

Metamorphosed pillow basalt (Ely Greenstone, Neoarchean, ~2.722 Ga; large glacial erratic along Main Street, Ely, Minnesota, USA) 2
by James St. John

Metamorphosed pillow basalt (Ely Greenstone, Neoarchean, ~2.722 Ga; large glacial erratic along Main Street, Ely, Minnesota, USA) 18
by James St. John

The City of Rocks National Reserve
by RuggyBearLA

Jaspilite banded iron formation (BIF) (Temagami Iron-Formation, Neoarchean, 2.736 Ga; iron mine at or near Temagami, southeastern Ontario, Canada) 2
by James St. John

Jaspilite banded iron formation (Soudan Iron-Formation, Neoarchean, ~2.722 Ga; Stuntz Bay Road outcrop, Soudan Underground State Park, Soudan, Minnesota, USA) 56
by James St. John

Metamorphosed pillow basalt (Ely Greenstone, Neoarchean, ~2.722 Ga; large glacial erratic along Main Street, Ely, Minnesota, USA) 16
by James St. John

Quartz-rich lapilli metatuff (quartz-rich meta-lapillistone) (Neoarchean, ~2.7-2.72 Ga; vicinity of Soudan Mine, Soudan, Minnesota, USA)
by James St. John

Metakomatiite lava flows (Upper Komatiitic Unit, Kidd-Munro Assemblage, Neoarchean, 2.710-2.718 Ga; Pyke Hill, near the Potter Mine, east of Timmins, Ontario, Canada) 51
by James St. John

Chlorite schist (Neoarchean; Soudan Mine, Soudan, Minnesota, USA) 2
by James St. John

End-Pleistocene large pothole in tholeiitic basalt (Clam Falls Volcanics, Mesoproterozoic, ~1.1 Ga; Bottomless Pit Pothole, Interstate State Park, Taylors Falls, Minnesota, USA) 4
by James St. John

North Star Mine (Hellroaring Plateau, Beartooth Mountains, Montana, USA) 2
by James St. John

The City of Rocks National Reserve
by RuggyBearLA