proterozoic

Shungite (Zaonezhskaya Formation, middle Paleoproterozoic, 1.98-2.09 Ga; Shun'ga River area, northwestern Russia) 7
by James St. John

Marcy Anorthosite (Mesoproterozoic, 1.16 Ga; Route 3 roadcut southwest of Saranac Lake, New York State, USA) 3
by James St. John

High-FeTi diabase dike (Duluth Complex, Mesoproterozoic, 1099 Ma; Twin Lakes East Skyline Parkway roadcut, Duluth, Minnesota, USA) 7
by James St. John

Olivine diabase (Silver Creek Cliff Sill, Proterozoic; Silver Creek Cliff, northeastern Minnesota, USA) 2
by James St. John

Banded iron formation
by James St. John

White Cap Pegmatite intruding schist (Proterozoic; White Cap Mine, east of Keystone, Black Hills, South Dakota, USA) 3
by James St. John

Copper crystal in copper mass (Mesoproterozoic, 1.05-1.06 Ga; Ahmeek, Upper Peninsula of Michigan, USA) 1
by James St. John

Jasper-quartz pebble conglomerate (Lorrain Formation, Paleoproterozoic, ~2.3 Ga; Pleistocene glacial clast derived from Canada) 8
by James St. John

Lakeshore beach gravel (upper Holocene; derived from the Split Rock intrusive felsite, Proterozoic; Iona's Beach, northeastern Minnesota, USA) 1
by James St. John

Nelsonite (Laramie Anorthosite Complex, Mesoproterozoic, 1.43 Ga; Sybille Pit, Laramie Range, Wyoming, USA) 13
by James St. John

Olivine diabase (Silver Creek Cliff Sill, Proterozoic; Silver Creek Cliff Tunnel, northeastern Minnesota, USA) 3
by James St. John

Pyritic nelsonite (Proterozoic; Port Leyden, western Adirondacks, New York State, USA) 12
by James St. John

Melt-matrix impact breccia (Vredefort Granophyre, 2.023 Ga, Paleoproterozoic; Vredefort Impact Structure, South Africa) 1
by James St. John

Copper and silver (Mesoproterozoic, 1.05-1.06 Ga; Adventure Mine, Ontonagon County, Upper Peninsula of Michigan, USA)
by James St. John

Granite & gneiss (Proterozoic; Mushroom Rocks, Rocky Mountains National Park, Colorado, USA)
by James St. John

Carbonatite (Iron Hill Carbonatite Complex, Neoproterozoic, >570 Ma; Iron Hill, Gunnison County, Colorado, USA) 15
by James St. John

Quartzite (Sioux Quartzite, Paleoproterozoic, 1.65 to 1.70 Ga; city of Sioux Falls, Transcontinental Arch, South Dakota, USA) 12
by James St. John

Copper (Mesoproterozoic, 1.05-1.06 Ga; Keweenaw Peninsula area, Upper Peninsula of Michigan, USA) 1
by James St. John

Labrador Antique Granite (anorthosite, Rogaland Anorthosite Complex, Mesoproterozoic, 929-932 Ma; near Egersund, Norway)
by James St. John

Magnetite skarn (Early Jurassic; French Creek Mining District, Chester County, Pennsylvania, USA)
by James St. John

Metanorthosite (Marcy Anorthosite, Mesoproterozoic, 1155 Ma; Rt. 73 roadcut near Chapel Pond, Adirondack Mountains, New York State, USA) 4
by James St. John

Large native copper amygdule (Mesoproterozoic, 1.05-1.06 Ga; Ahmeek Mine, Ahmeek, Upper Peninsula of Michigan, USA) 1
by James St. John

Lakeshore beach gravel (upper Holocene; derived from the Split Rock intrusive felsite, Proterozoic; Iona's Beach, northeastern Minnesota, USA) 23
by James St. John

Phyllite (French Slate, Paleoproterozoic; Snowy Range Road roadcut, Medicine Bow Mountains, Wyoming, USA) 8
by James St. John

Copper (Mesoproterozoic, 1.05-1.06 Ga; Keweenaw Peninsula area, Upper Peninsula of Michigan, USA) 2
by James St. John

Lakeshore beach gravel (upper Holocene; derived from the Split Rock intrusive felsite, Proterozoic; Iona's Beach, northeastern Minnesota, USA) 21
by James St. John

Radioactive quartz-pebble conglomerate (Matinenda Formation, Paleoproterozoic, ~2.3-2.48 Ga; Spine Road outcrop, Elliot Lake, Ontario, Canada) 2
by James St. John

Sandstone injectite with granite pebbles (Tava Sandstone, Neoproterozoic; west of Woodland Park, Colorado, USA) 4
by James St. John

Percussion marks (Sioux Quartzite, Paleoproterozoic, 1.65-1.70 Ga; Falls Park, Sioux Falls, South Dakota, USA) 7
by James St. John

Copper (Mesoproterozoic, 1.05-1.06 Ga; Keweenaw Peninsula area, Upper Peninsula of Michigan, USA) 4
by James St. John

Lakeshore beach gravel (upper Holocene; derived from the Split Rock intrusive felsite, Proterozoic; Iona's Beach, northeastern Minnesota, USA) 2
by James St. John

Quartzite & slate (Baraboo Quartzite, upper Paleoproterozoic, ~1.7 Ga; Van Hise Rock, just north of Rock Springs, Wisconsin, USA) 6
by James St. John

Crushed Sioux Quartzite (upper Paleoproterozoic, 1.65-1.70 b.y.) in concrete (Chamberlain, South Dakota, USA) 6
by James St. John

Pyrrhotite-pentlandite-chalcopyrite-magnetite (Paleoproterozoic, 1.85 Ga; Worthington, Sudbury Impact Structure, Ontario, Canada) 2
by James St. John

Coarsely-crystalline porphyritic granite (Pikes Peak Batholith (pgpm2 facies), Mesoproterozoic, 1.08 Ga; a little east of summit house atop Pikes Peak, central Colorado, USA) 1
by James St. John

Old iron mine & nelsonite rocks (Proterozoic; Port Leyden, western Adirondacks, New York State, USA) 6
by James St. John

Native copper-replaced cross-bedded sedimentary rocks (Nonesuch Shale, Mesoproterozoic; White Pine Mine, Upper Peninsula of Michigan, USA) 4
by James St. John

Anorthosite (Ankafotia Anorthosite Massif, Neoproterozoic, ~660 Ma; Madagascar) 14
by James St. John

Grypania spiralis (Negaunee Iron-Formation, 2.11 Ga or 1.874 Ga; Empire Mine, SE of town of Ishpeming, Marquette County, Upper Peninsula of Michigan, USA) 02
by James St. John

Mountain Green Granite (garnetiferous metanorthosite, Marcy Anorthosite, Mesoproterozoic, 1.155 Ga; Cold Springs Granite Quarry, near Jay, Adirondacks Mountains, New York State)
by James St. John

Carbonatite breccia (Fen Complex, Ediacaran-Early Cambrian, 523-601 Ma; near Ulefoss, Norway) 2
by James St. John

Villiaumitic lujavrite (Illímaussaq Complex, late Mesoproterozoic, 1.16 Ga; Kvanefjeld, southern Greenland) 4
by James St. John

Native copper from intraclast conglomerate matrix (Mesoproterozoic, 1.05-1.06 Ga; Conglomerate Lode, Centennial Mine, Houghton County, Michigan, USA) 1
by James St. John

Tenorite-chrysocolla (Proterozoic; Algomah Mine, Upper Peninsula of Michigan, USA) 1
by James St. John

Coarsely-crystalline porphyritic granite (Pikes Peak Batholith (pgmc facies), Mesoproterozoic, 1.08 Ga; Pikes Peak Cog Railway parking lot, central Colorado, USA)
by James St. John

Layered gabbros (troctolitic series, Duluth Complex, Mesoproterozoic, 1099 Ma; Thomson Hill Information Center Outcrop, Skyline Parkway, Duluth, Minnesota, USA) 5
by James St. John

Magnesite-dolomite rock (Stensgar Dolomite, upper Mesoproterozoic; Red Marble Quarry, Washington State, USA) 4
by James St. John

Muscovite schist (Paleoproterozoic; Black Hills, South Dakota, USA) 3
by James St. John

Silicified stromatolite boundstone with oolites & sinuous stromatolites (Biwabik Iron-Formation, Paleoproterozoic, ~1.878 Ga; near Mary Ellen Mine, near Biwabik, Minnesota, USA) 1
by James St. John

Black porphyritic metarhyolite (Utley Rhyolite, Paleoproterozoic, 1765 Ma; Utley Rhyolite Quarry, near Green Lake, Wisconsin, USA) 4
by James St. John

Stromatolite (Dresser Formation, Paleoarchean, 3.48 Ga; Normay Mine, North Pole Dome, Pilbara Craton, Western Australia) 3
by James St. John

Moonstone (iridescent peristerite-oligoclase feldspar) (Chupa Pegmatite Field, Mesoproterozoic, 1.75 to 2.10 Ga; at or near Chupa Bay, Karelia, Russia) 2
by James St. John

Lakeshore beach gravel (upper Holocene; derived from the Split Rock intrusive felsite, Proterozoic; Iona's Beach, northeastern Minnesota, USA) 24
by James St. John

Copper crystal in copper mass (Mesoproterozoic, 1.05-1.06 Ga; Ahmeek, Upper Peninsula of Michigan, USA) 2
by James St. John

Muscovite schist (Paleoproterozoic; Black Hills, South Dakota, USA) 1
by James St. John

Pyritic nelsonite (Proterozoic; Port Leyden, western Adirondacks, New York State, USA) 10
by James St. John

Toasted Almond Granite (granulite, Proterozoic; near Ghibli, Tamil Nadu State, Eastern Ghats Orogenic Belt, India)
by James St. John

Proglacial lacustrine rhythmitic argillite (Konnarock Formation, Neoproterozoic, ~750 Ma; Grassy Branch Outcrop - Rt. 603 roadcut, Smyth County, Virginia, USA)
by James St. John

Olivine diabase (Silver Creek Cliff Sill, Proterozoic; Silver Creek Cliff, northeastern Minnesota, USA) 4
by James St. John

Pegmatitic granite (alaskite) (Mt. Morrison Granite, late Paleoproterozoic, 1.7 Ga; Carpenters Peak, Roxborough State Park, Front Range, Colorado, USA) 1
by James St. John