Some Proterozoic Rocks 1
Biwabik Iron-Formation - 2.3 Ga stromatolitic ferruginous chert from the Mesabi Iron Range of northern Minnesota, USA.
Lorrain Quartzite - 2.3 Ga quartzite from Manitoulin Island, Ontario, Canada.
Hotazel Formation - 2.2-2.3 Ga sugilite (purple) and ~2.05 Ga sedimentary manganese-oxide rock (dark brown) from the Kalahari Manganese Field, South Africa.
Mesnard Quartzite - 2.2-2.29 Ga metaquartzite from Marquette, Michigan’s Upper Peninsula, USA.
Kona Dolomite - 2.2-2.29 Ga silicified metadolostone from southwest of Marquette, Michigan’s Upper Peninsula, USA.
Wewe Slate - 2.2-2.29 Ga slate from the Ragged Hills, Michigan’s Upper Peninsula, USA.
Silver from a 2.217 Ga (~mid-Paleoproterozoic) hydrothermal vein intruding the Gowganda Formation (Paleoproterozoic, 2.288 Ga) at McKinley-Darragh Mine, Ontario, Canada.
Ajibik Quartzite - 2.1-2.2 Ga metaquartzite from the Ragged Hills, Michigan’s Upper Peninsula, USA.
Siamo Slate - 2.1-2.2 Ga slate from near Mud Lake, Michigan’s Upper Peninsula, USA.
Negaunee Iron-Formation - 2.11 Ga (or 1.874 Ga) jaspilite (left) & specularite-quartzite BIF (center) & specularite (right) from the Marquette Iron Range, Michigan’s Upper Peninsula, USA.
Negaunee Iron-Formation - 2.11 Ga (or 1.874 Ga) fossiliferous ferruginous mudshale from the Empire Mine, Michigan’s Upper Peninsula, USA.
Vulcan Iron-Formation - 2.1 Ga jaspilite BIF from Vulcan, Michigan’s Upper Peninsula, USA.
Minas Supergroup (“Hollywood Granite”) - Paleoproterozoic-aged folded jaspilite meta-iron formation (meta-BIF) from the Iron Quadrangle District, Minas Gerais State, Brazil.
Bushveld Complex (“Impala Black Granite”) - 2.054-2.061 Ga gabbronorite from Rustenburg, South Africa.
Bushveld Complex - 2.06 Ga chromitite from the Mooinooi Mine, South Africa.
Phalabowra Complex - 2.06 Ga calciocarbonatite with magnetite-chalcopyrite-bornite (copper ore) from the Loolekop Pipe, South Africa.
Vredefort Granophyre - 2.023 Ga melt-matrix impact breccia from Vredefort Impact Crater, South Africa.
Homestake Formation - 1.9-2.0 Ga auriferous greenschist from the Homestake Mine, town of Lead (pronounced “Leed”), northern Black Hills, South Dakota, USA.
Homestake Formation - 1.9-2.0 Ga gold ore from the Homestake Mine, town of Lead (pronounced “Leed”), northern Black Hills, South Dakota, USA.
Left: ~3.5 cm across. Right: ~1.25 cm across.
Beaver Bay Complex - pre-1.9 Ga anorthosite xenolith (inclusion) hosted in 1.13 Ga intrusive igneous rocks of the Beaver Bay Complex, northeastern Minnesota, USA.
Lower Middleback Iron-Formation - 1.859-1.945 Ga banded iron formations (BIFs) from near the Iron Duke Mine, South Australia.
“Verde Lavras Granite” - 1.9 Ga orthogneiss (metamonzogranite) from Lavras, Minas Gerais State, southeatern Brazil.
Flambeau Volcanogenic Massive Sulfide Deposit - Paleoproterozoic volcanogenic massive sulfide rock from the Flambeau Mine, northwestern Wisconsin, USA.
Ironwood Iron-Formation - 1.874-1.878 Ga jaspilite BIF from Wakefield, Michigan’s Upper Peninsula, USA.
Michigamme Formation - 1.85-1.86 Ga schist from Lake Michigamme, Michigan’s Upper Peninsula, USA.
Sudbury massive sulfides - 1.85 Ga chalcopyrite (left) & pentlandite in pyrrhotite (right) from the Sudbury Impact Structure, Ontario, Canada.
Black Onaping Impact Breccia - 1.85 Ga impact breccia from the Sudbury Impact Structure, Ontario, Canada.
Akluilâk Dike - 1.832 Ga microdiamondiferous ultrapotassic minette from the Gibson Lake area, “Nunavut”, northern Canada.
Nalunaq Gold Ore - 1.77-1.80 Ga quartz-gold vein in calc-silicate altered wall rock from the Nalunaq Gold Mine, southern Greenland.
Santa Elena Placer Gold Deposit - 1.7-1.8 Ga gold crystal in modern placer, but derived from the Uairén Formation in Bolivar State, southeastern Venezuela.
Yinnietharra Pegmatite - 1.48 to 1.80 Ga dravite tourmaline from pegmatitic granite near Yinnietharra Station Homestead, Western Australia.
Volodarsk-Volhynsky Intrusion - 1.758-1.760 Ga anorthosite from the Korosten Pluton in Zhitomir Province, northwestern Ukraine.
Thackaringa Group - 1.688-1.710 Ga albitite from Thackaringa, New South Wales, southeastern Australia.
Willyama Supergroup - 1.66 Ga tourmalinite (= banded rock at left) with Cambrian-aged, argentiferous galena hydrothermal vein (= silvery-colored material at right) from the Umberumberka Mine, New South Wales, Australia.
Wiborg Batholith (“Baltic Brown Granite” (wiborgite) & “Baltic Red Granite” (pyterlite) - 1.615-1.645 Ga rapakivi granites from southern Kymi Province, southern Finland.
Broken Hill Block - gahnitic granite from the early Mesoproterozoic at Southern Cross, New South Wales, Australia.
Nine Mile Granite - 1.505 Ga granite (with pinkish K-feldspar, dark gray quartz, and black biotite mica) from the Ladick Quarry, southern Marathon County, north-central Wisconsin, USA.
Aldridge Formation - 1.47 Ga banded silver-lead-zinc-ore (massive sedimentary exhalative sulfide deposit - SEDEX) from the Sullivan Mine, British Columbia, Canada.
Mount Evans Batholith - 1.44 Ga alaskite granite (with pinkish K-feldspar and whitish-gray quartz) from near the summit of Mt. Evans, Clear Creek County, WSW of Denver, central Colorado, USA (7.8 cm across at its widest).
Laramie Anorthosite Complex - 1.43 Ga nelsonite from the Laramie Range, southeastern Wyoming, USA.
“Kashmir White Granite” - 1.4 Ga garnetiferous granulite from Melur Taluk, Tamil Nadu State, far-southern India.
Nain Plutonic Suite (“Blue Eyes Granite”) - 1.29-1.35 Ga anorthosite from Ten Mile Bay Quarry, Labrador, eastern Canada.
Voisey’s Bay Ni-Cu-Co Magmatic Sulfide Deposit - 1.333 Ga sulfidic gabbro from the Nain Plutonic Suite at Voisey’s Bay Mine, Labrador, eastern Canada.
Allamoore Formation - 1.25 Ga talcose metamorphite from the Bridges Talc Mine, Allamoore, far-western Texas, USA.
“Madocite” - 1.24 Ga tourmaline-pyrite metamorphite from Madoc, southeastern Ontario, southeastern Canada.
Premier Kimberlite Pipe - 1.2 Ga kimberlite from the Premier Mine, South Africa.