Competition from the synthetic diamond market has affected the current value of natural diamonds, which range from less than $1 per carat for small industrial-grade diamonds to many thousands of dollars per carat for the best colored, gem-quality natural stones. This diabase rock is much harder than the original basalt causing it to errode much less. This created a low basin into which streams rapidly brought gravel, sand and mud eroded from the newly formed volcanic rocks. It has a current market value of around $6 per pound, making it an extremely attractive metal to mine. KIRK JOHNSON: How much basalt is down there? Search Events Most locals simply call them Presque Isle Stones. We see these sandstones today making up the Bayfield Peninsula and Apostle Islands, the north shore of the Keweenaw and the southeast part of Isle Royale. How it got there: Agates formed when silica-rich solutions filled cavities produced by gas bubbles in basaltic lava flows more than 1 billion years ago. About one-third of all current silver production is used in the manufacture of photographic film and paper, although its use in the photo industry has been diminished by the introduction of digital cameras. Basalt underlies more of Earth's surface than any other rock type. Although the present Lake Superior was sculpted by much more recent glaciers—most recently about 10,000 years ago—its location reflects the geometry of the ancient rift below it (see fig. 10.What might have stopped the rift in our continent? Both occur along beaches of Lake Superior, on Michigan's upper peninsula. As the lithosphere above stretched and rifted, the hot plume rock started to melt as it encountered the lower pressures near the surface. Over the past few centuries, gold has been discovered in Ontario, for example, the Red Lake area, near Geraldton and more recently at Hemlo, near Wawa. Collectors seek many Lake Superior minerals for their beauty, aesthetic qualities or rareness. What it’s used for: Magnetite is the major ore mineral recovered in the taconite industry. Similarity in their melting temperatures and high densities cause them to crystallize from a cooling magma at about the same time and settle into layers with other high-temperature minerals. Let’s look way back into our more ancient geological history for the explanation. Magnetite from the Kinney Mine, Buhl, Minnesota. Gold also has been mined near Ishpeming, Michigan. It has a maximum depth of 1,332 feet (406 meters). Many of the abandoned mine dumps within the Keweenaw Peninsula are made of blocks of basalt lava rock. These heavily veined cobble beach stones came from Presque Isle Park in Marquette, Michigan of Upper Michigan bordering Lake Superior. The vast expanse of clear water, the brooding cliffs of the northern shores, black boulders crowded along some beachfronts or the paler, shifting sands of others? This plume (as illustrated on the bottom of this page) apparently centered under where Lake Superior is today and, in fact, determined where our Great Lake would eventually develop. Basalt is a dark-colored, fine-grained, igneous rock composed mainly of plagioclase and pyroxene minerals. Lake Superior agates: From find to finish For agate collectors, the search is a hunt for buried treasure. Basalt is found on the lakeshore at Town Park and Lighthouse Point in Two Harbors. So it is that billions of years went into making the wealth of minerals on or close to Lake Superior’s shores. Some contain the great iron-bearing strata whose ores have supported a world-class mining industry for more than a century. Like hematite, it occurs as fine earthy material and in globular masses. The universal attraction of gold has lured prospectors to Lake Superior, and some have been lucky and successful. Fascinating facts and photos featuring the most common beach stones found along Lake Michigan shorelines, as well as several unusual kinds; includes various types of basalt, septarian, limestone, granite, gabbro, diorite, gneiss, schist, sandstone, silt … The greatest nickel deposits in the world occur in the Sudbury, Ontario, area about 180 miles east of Sault Ste. About Basalt, broken; 1 cubic meter of Basalt, broken weighs 1 954 kilograms [kg] 1 cubic foot of Basalt, broken weighs 121.98424 pounds [lbs] Basalt, broken weighs 1.954 gram per cubic centimeter or 1 954 kilogram per cubic meter, i.e. When it erupts and solidifies, this kind of magma produces a rock called basalt. They are used in high-tech electronics, surgical instruments, photography and jewelry. Jan 15, 2020 - Explore Chris Bowen's board "Lake superior" on Pinterest. Copper occurs here in a wide variety of crystal forms, producing spectacular display specimens. It forms large ore bodies on some iron ranges in the Lake Superior area. Gene L. LaBerge, One brief period of compression squeezed up parts of the middle of the rift along the great Keweenaw and Isle Royale faults. The North Shore of Lake Superior in Minnesota lies on the north side of the Midcontinent Rift System which ran 1,300 miles northwest; through what is now Lake Superior, and southwest. Black granite - a trade name that is a horrible misnomer. Called basalt, this volcanic rock is seen here at Temperance River State Park in Minnesota and can be found in all the state parks along Lake Superior’s Minnesota shore. Marie. How it got there: Diamonds form deep below the Earth’s crust in the upper mantle, where heat and pressure are sufficiently high to make it the stable form of carbon. Keep up with the magazine, news and happenings around the Big Lake. It most commonly forms as an extrusive rock, such as a lava flow, but can also form in small intrusive bodies, such as an igneous dike or a thin sill. Hematite from Tracy Mine, Negaunee, Michigan. The volcanic and granitic rocks tell us of the building of great mountain ranges, perhaps rivaling the Alps but which have since been eroded to the nub. All rights reserved. Called a “plume,” this rising cylinder of hot mantle rock came up and spread out under the stiffer lithosphere (the crust and uppermost mantle). Found mostly along Lake Superior’s Ontario shores and located in the area called the Superior Province of the Canadian Shield, these ancient rocks date from the Archean Eon. The region is world famous for vast deposits of iron ore and native copper. In Duluth, look around at Leif Erikson Park or at Amity Creek and Lester River. What might have stopped the rift in our continent? more than 1 year ago, Search Events Sort by Featured Best selling Alphabetically, A-Z Alphabetically, Z-A Price, low to high Price, high to low Date, old to new Date, new to old The dark basalt flows are evidenced in many areas. That is for basic food, clothing and shelter as well as resources to build roads traveled and recreational facilities enjoyed. One source I found states it is serpentinized peridotite (serpentinite rock) of the Mona Formation, Archean in age - 2.6 billion years. The famous Palisade Head and Shovel Point are made of light-colored volcanic flows called rhyolite. Then about 1.1 billion years ago a whole new geological revolution began that changed central North America forever. How it got there: It is believed that the iron formations in which magnetite occurs formed by chemical precipitation in ancient seas nearly 2 billion years ago. Because of its high conductivity, silver is still widely used in electronics. Extensive taconite operations are on the Mesabi Range in Minnesota, and to a lesser extent on the Marquette Range in northern Michigan. Note the Earth’s curvature for scale. The river beds of the Temperance and Cascade are also carved from basalt. Basalt has a strict chemical definition. Eventually, for reasons not yet well understood, the plume in our ancient region became inactive, and magma production and rifting ceased. The Rift is nearly 1400 miles long extending from northeast Kansas to Lake Superior with an eastern arm curving around and heading toward Ohio (part of a Triple Junction, more geology jargon). To develop the proper perspective, we need to travel into “deep time” – geologic time – measured in billions of years. How much Basalt is below Lake Superior? Like hematite and goethite, magnetite ranges in value from less than $1 per pound for ore-grade material to several hundred dollars for fine, crystallized specimens (uncommon in this region). With its rich history of providing mineral wealth, the Lake Superior region will no doubt continue to be a rock-solid resource to the world. Within the region it is unique to the Keweenaw native copper deposits. Here are just a few lake places where evidence of the fiery past can be seen: The ropy surface of a basalt flow above a pool at the mouth of the Temperance River. Marie are made of volcanic basalt flows as are the shores of the islands south and west of Rossport, the Black Bay Peninsula south of Nipigon and Michipicoten Island. How it got there: Like the native copper with which it occurs, datolite formed when hydrothermal solutions invaded open fractures in the basaltic rocks of the Keweenaw Peninsula in Michigan more than a billion years ago. The northern two-thirds of Isle Royale features the Greenstone Ridge, a huge ancient lava flow. Throughout the lake basin there are examples of volcanic activity on the cliffs above you to the rock beneath your feet. Others have a sedimentary origin, born from deposition of sand, mud and gravel in long-vanished seas. This “baker’s dozen” represents a fraction of the minerals and metals harbored in the rocks of Lake Superior. A great place to see minerals: The A.E. Lake Superior region rocks also record long periods of erosion that reduced the mountain ranges to rather flat lowlands and produced yet another generation of minerals. Lesser amounts have been found in similar rocks on Isle Royale and Ontario’s Algoma District. Oxygen required to precipitate the iron was provided by photosynthetic algae, the remains of which are preserved in these rocks as some of the world’s oldest-known fossils. A nickel deposit was mined recently near Lake Shebandowan west of Thunder Bay. The deepest point in Lake Superior is 1,300 feet (400 meters) below the surface, making a complete freeze a rarity. This is the same dark volcanic rock that makes up nearly all of the volcanic islands we know today, such as Hawaii and Iceland. As mineral-rich water circulated through the cavities, silica (SiO 2), or quartz, was deposited in layers along cavity walls. • 109 W. Superior St. #200 • Duluth, MN 55802 • 218-722-5002 • edit@LakeSuperior.com. This post was originally published on this site. What it is: “Native” copper is naturally occurring, pure, metallic copper. It is 350 miles (563 km) long (east to west), and its greatest width is 160 miles (258 km) from north to south. These metals have recently been discovered in northeastern Minnesota, in the Lake Nipigon area of Ontario and in the Marquette area. The result is a high cliff above Lake Superior that was able to withstand the effects of glaciers and other erosion. As the plume slowly rose and spread out, two important processes began. This great mass consists of rocks formed in Precambrian times – that is, from the very origin of Earth about 4.7 billion years ago up to a mere 545 million years ago. The value of refined copper is about $1.80 per pound, but a fine, one-pound crystallized specimen may be worth more than 1,000 times that to a serious collector. How it got there: PGEs typically occur in layered igneous rocks that formed deep below the Earth’s surface. Most native copper mines produced some native silver. This left the tilted, upturned edges of the harder lava flows around the margins, with the middle of the rift occupied by several miles of overlying sedimentary rock, mostly sandstone. The region holds fame in another geologic camp. Its current value ranges from less than $1 per pound for decorative rock to several hundred dollars for cut gems or fine collectors’ specimens. Magma that comes from partial melting of the Earth’s mantle has a particular chemical composition. Several commercial prospects are being evaluated in the Wawa, Ontario, area. Outstanding regional minerals form private and public collections worldwide and close to home at the A.E. Over 300 streams and rivers empty into Lake Superior. These rocks were shoved and tilted and can be seen especially between Marquette and Ironwood in Michigan and in the tilted formations in Jay Cooke State Park south of Duluth. BUILDING COASTLINE S – East Coast – (25:10-31:25) 27.39What turned the original mud of Manhattan into hard rock (schist)? What it is: Chlorastrolite is a special variety of the mineral pumpellyite. What it is: Magnetite, or black iron oxide (Fe3O4), is a major constituent of the rock called “iron formation,” from which the natural ore bodies of hematite and goethite formed by chemical weathering over millions of years. They are being mined near Lac des Illes, Ontario. They are used as catalysts in the chemical and petroleum industry – and in catalytic converters in the exhaust systems of automobiles. It has a composition similar to gabbro. A stop at the state Tourism Information Center in Ironwood features a parking area where the walls are made of local basalt lava rock. You see the dramatic and aesthetic beauty of the landscapes that keep many of us here and keep others coming back. During the last 150 years, the rocks have yielded immense tonnages from those deposits and attracted early settlers to the iron and copper mines. • 109 W. Superior St. #200 • Duluth, MN 55802 • 218-722-5002 • edit@LakeSuperior.com. How much Basalt is below Lake Superior? 11.What turned the original mud of Manhattan into hard rock? In our area, the oldest rocks are about 2.7 billion years old. It is an official provincial gemstone of Ontario. These are the remaining records of an exciting history of volcanic activity, slow depositions of sedimentary rocks in ancient seas and the building of mountains from huge volumes of rising molten granite that heated the rocks they invaded, re-organizing chemical ingredients to form new minerals and producing hot fluids that moved upward and deposited other minerals. Basalt is formed when lava rich in iron and magnesium erupts onto the earth's surface, cooling into a fine grained dark colored rock. What it’s used for: Amethyst is used as a decorative building stone in the Thunder Bay area, as “gem rough” to make jewelry and as spectacular display specimens for mineral collectors. Just below the Devil’s Kettle is another small falls you can go down a long flight of around 180 stairs to see. The close association of these two metals was somewhat distinctive to the region. For more than 35 years, he has focused on the volcanic rocks of Lake Superior’s Minnesota north shore. Amethyst from the Diamond Willow Mine near Pearl, Ontario. In May 2000 in Thunder Bay, Ontario, the Institute on Lake Superior Geology awarded him the S.S. Goldich medal for work on the geology of the Lake Superior area. How it got there: Like agate, chlorastrolite formed when mineralizing fluids filled gas cavities in basaltic lava flows. ... (the same process that creates the nice sandy bottom of Lake Superior at Park Point). Sperrylite (a platinum mineral) with chalcopyrite from the Vermilion Mine, Sudbury, Ontario. Values can range from less than $1 to several thousand dollars for a single specimen, depending on its size, pattern and overall quality. PGEs may be associated with some massive sulfide deposits. Daisy stone - basalt with rosettes of feldspar from near Mamainse Point, north of Pancake Bay, which is on Lake Superior, about 60 miles north of Sault Sainte Marie, Ontario, Canada (Brummer 1980, p.2375). Dr. Robinson is the former curator of the A.E. Ginanda-nisidotaadimin: Understanding American Indian History Series - Understanding Tribal Sovereignty. Similarly, Lake Superior is largely rimmed by these billion-year-old basaltic lava flows that gave us the Keweenaw Peninsula and Isle Royale, Michigan, Michipicoten Island and Mamainse Point, Ontario, and Minnesota’s north shore. Fewer rocks and fewer places to search don't diminish the thrill. As the granitic crust was torn apart by continental drift, lava flowed out from 30–60 miles (50–100 km) under the crust and formed basalt. This formed a huge valley, about 200 miles long and 100 miles wide Like copper, native silver occurs in many crystal forms, yielding exquisite display pieces for collectors. What it is: Datolite is a hydrous calcium boron silicate that occurs in a wide range of colors. What it is: Red iron oxide (Fe2O3) occurs as very fine, “earthy” material, in globular masses, or as fine-to-coarse crystals with a metallic luster. But the stage had now been set for the final act of the geologic drama that produced Lake Superior – the time during the past 2 million years when the Lake Superior basin itself would take shape as time and again the mighty ice sheets excavated the softer sedimentary rocks that occupied the center of the rift. Co-author Bob Lynch is owner of Agate City Rocks and Gifts in Two Harbors Minnesota. 'http':'https';if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src=p+"://platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); A Great Lakes Information Network partner, ©2020 Lake Superior Publishing LLC. Chlorastrolite from Isle Royale, Michigan. Our regional ores were critical in helping the Allies win World Wars I and II. Amethyst is recovered from veins in granite and other rocks around Thunder Bay, Ontario, and to a lesser extent from Michigan’s Keweenaw Peninsula. Native Copper from Silver Islet, Thunder Bay District, Ontario. But so much heavy basalt had been transferred from beneath the crust onto the surface, that the land continued to sink along the axis of the rift. Native Gold in Quartz from the Michigan Gold Mine near Ishpeming, Michigan. Seaman Mineral Museum at Michigan Technological University in Houghton. The deepest point in Lake Superior (about 40 miles north of Munising, Michigan) is 1,300 feet (400 meters) below the surface. Thus began an intense period of volcanic eruptions that continued – with only one 5 million-year pause – for about 24 million years. Copper has been mined in the Keweenaw by European settlers since the mid-1800s, but it was long known by the indigenous peoples. It is a state gemstone for Michigan. Kelly Watkins But don’t think that this volcanic activity was similar to what we see in Hawaii today. Most is cut and polished for collectors, jewelry or scrimshaw art. Being a Rockhound and with the many agates I have, I knew there was more than just Agates and Thompsonite. The current value ranges from cents per pound of ore-grade hematite to several hundred dollars for high-quality collector’s specimens of similar size. Lake Superior Rocks & Minerals: A Field Guide to the Lake Superior Area. The magnetite concentrate is converted into pellets and shipped to smelters to produce iron for the steel industry. None of these huge, world-class lakes would exist if the Great Ice Age glaciers had not scooped out the basins where they now lie. The earliest lake recognized in the Superior basin, Lake Keweenaw, formed around 12,000 years ago but only lasted about 200 years before the ice came back again. Explosive eruptions of the volcanic rock known as kimberlite carry the diamonds to the surface. Native Silver from Silver Islet, Thunder Bay District, Ontario. Agate from Keweenaw Point, Keweenaw Co., Michigan. Steel is used extensively in the construction and automobile industries and in manufacture of an innumerable variety of machinery, utensils and cutlery and such mundane items as nails, screws and bolts. It is naturally magnetic; hence its name. Most areas within Earth… Check out Michigan Gold & Silver, Dan Fountain’s book about the search for precious metals in the Upper Peninsula. They make distinctive jewelry. These sedimentary rocks formed in a large sea and the rocks today can be found in Michigan’s Upper Peninsula, west of Duluth and to Cloquet and on the Mesabi Range in Minnesota and around Thunder Bay, Ontario. Back 1.1 billion years ago, the earth began a shimmy, shake and split along a 1,800-mile arch that looked to be well on its way to creating a continental divide that literally would have divided into two continents. Its value is comparable to hematite, though it contains slightly less iron. The copper also has been extensively used in electrical wire and instruments and in alloys, such as brass. It is defined in the TAS diagram shown above. We introduce here a sampler, a “baker’s dozen,” of significant Lake Superior minerals, metals and gems chosen for their monetary or collector value. A rich sulfide ore deposit containing economic concentrations of nickel and other metals has been discovered near the Huron Mountains in northern Michigan. Gas bubbles in basalt set the stage for formation of Thomsonite and for Lake Superior agates. V. Lake Superior Rocks! Submit Yours. What it’s used for: The vast majority of nickel mined today is used to make stainless-steel and other corrosion-resistant alloys, as well as nickel-cadmium batteries. Although Lake Superior itself was sculpted by much more recent glaciers, most recently about 10,000 years ago, its location reflects the geometry of the ancient rift. When the last of the ice melted – about 10,000 years ago – Lake Superior was born. Ginanda-nisidotaadimin: Understanding American Indian History Series - Understanding Tribal Sovereignty, The Lake Superior Basin's Fiery Beginning. Lake Superior Geology. What it’s used for: The attractive color banding of Lake Superior agates makes them widely prized by collectors and lapidarists. Check out the falls above and below Highway 61 at Gooseberry Falls or the lakeshore southwest of the Split Rock Lighthouse. Depending on size, pattern and quality, the value ranges from a few dollars to more than $1,000 for the best larger gem-quality stones. The thickness can vary between 2000 m (Deccan Traps, India) and 12,000 m (Lake Superior, North America). Continental flood basalts, derived from mantle plumes rising from the deep core–mantle boundary, are major hosts for world-class large-scale Ni-Cu-PGEs ore deposits ( Zhang et al., 2008 ). What it’s used for: Hematite is a major ore of iron, which is used for making steel and cast iron. Lake Superior is a vast fresh water resource that has not experienced the same levels of development, urbanization and pollution as the other Great Lakes.Recognizing the unique qualities of this resource, the United States and Canada are working to restore and protect the Lake Superior Basin. DVD: How to Find Agates. Get the best deals on Lake Superior Agate when you shop the largest online selection at eBay.com. Huge amounts of melt (magma) were produced and the fissures in the rifting crust allowed the magma a passage to the surface. Rocky outcrops along Lake Superior reveal spectacular vistas. Made of pure carbon, it is the hardest naturally occurring mineral. The greatest occurrence of native copper in the world  is in the basaltic volcanic rocks and interlayered sediments on Michigan’s Keweenaw Peninsula. Some are more than 2 billion years old. 7. Because the soft sediment filling the rift is much easier to erode than the harder basalt. But those areas to the east did not share the dramatic volcanic history of the Lake Superior basin. Minnesota's state gemstone is the Lake Superior agate—so named because it is found predominantly along the shore of Lake Superior. Based on the “record of the rocks,” then, what ancient landscapes can we conjure for the Lake Superior area? The rocks of the Lake Superior region, some of the oldest in the world, formed over a vast expanse of geologic time and by a wide variety of geologic processes. At Seventh Street west of Agate Street in Houghton, the hill there is made from a large basaltic flow. The current values range from a few dollars for small, white nodules to several thousand dollars for larger, fracture-free, colored varieties. These dark rocks, familiar around Lake Superior, are evidence of ancient volcanic activity. Agates formed in cavities in basalt. But still no hint of the dramatic events that set up conditions for the eventual creation of Gitchi gami, the biggest lake of all. Dr. LaBerge is the author of Geology of the Lake Superior Region and is professor emeritus of geology at the University of Wisconsin-Oshkosh.
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