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Structure
Interesting Questions, Facts and Information
- There are a total of 95 general entries. We are selecting 30 for display.
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 Interesting Questions, Facts, and Information
 Geology
Madoc, Ontario. The Madoc area of Ontario had the first gold mine in Canada, but there was so little gold that the mine was never very large, and gold in the Madoc area 'ran-out' before 1900.
komatiitic volcanic flows. Magmatic nickel-copper deposits are only found within these four deposit sub-types. Komatiitic volcanic flows is not a common sub-type in the world.
nickel, copper . The Thompson district of northern Manitoba is well known for its vast quantities of nickel and copper, and it is one of the largest deposit of its kind in the world.
Cu-Co-Ag-Au. This is a common mineral-metal assemblage, with copper being the most abundant metal.
| What is the name of the largest Besshi-type volcanogenic massive sulphide in the world, located in northwestern British Columbia? | Canadian Mineral Deposit Geology
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Windy Craggy . This deposit, the largest of its kind in the world at 300 Million tonnes of metals, was prematurely shutdown in 1995 because of environmental concerns. Many of the environmental problems discerned by the environmentalist groups could have in fact been solved, and thus there should be mines in this region today. However, there never will be, because the region (and deposit) is now a UNESCO World Heritage Site.
Lead and zinc. These two metals are the two main metals found in any Mississippi Valley Type deposit. They are what define the deposits themselves.
Mississippi Valley Type. This mine is now shutdown (a fairly short time ago), but played an important role in Canada's yearly production of zinc and lead.
Yes . Contrary to common belief, the ores of the Sudbury are not located in the Sudbury Igneous Complex, rather they are located in the offset dikes, which rim the rocks of the Sudbury Igneous Complex. Most of the Sudbury mines are located in these offset dikes, with a few being located in the Sudbury Igneous Complex itself.
volcanogenic massive sulphide. The Kidd Creek deposit also plays a very important role in Canada's yearly copper, zinc, and lead production. It is considered a Giant deposit, and the shafts of the mine run very deep into the ground.
manto type, lode gold deposit. The Hemlo deposit is one of the richest and most well-known gold deposits in Canada, and the mines at Hemlo play a very important role in Canada's yearly gold production.
founder of the Smithsonian Institution. Smithsonite was named after John Smithson, an Englishman who donated funding for the establishment of the Smithsonian Institution.
ulexite. Each fiber of ulexite transmits light and images, thus it paved the way for the invention of fiber optics by transmitting images along a bundle of threadlike crystals.
aurichalcite. Aurichalcite is derived from an ancient word meaning brass. It actually is so close to brass alloy, that it could be considered as a natural brass ore. It is a very rare mineral so it probably will never serve this purpose.
acanthite. Argentite has a cubic structure at temperatures above 180 degrees Celsius. It had to form at all temperatures higher than this, thus all argentite specimens are pseudomorphs after the original mineral argentite referred to as acanthite (orthorhombic).
| What mineral has an index of refraction so close to water that when placed in water it becomes invisible? | Interesting Mineral Facts
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cryolite. Cryolite has a low ability to bend light, being close to water in that aspect. When placed in water it appears invisible; however it will eventually dissolve since cryolite is soluble in water.
20%. Only about 20% of the mined world's diamonds are suitable for the gem trade. The remaining ones are used for industrial purposes such as saw blades or abrasives.
apatite. Bone and teeth have essentially an apatite structure and composition. Apatite has a hardness of 5, compared to a diamond which has a hardness of 10.
imps or gremlins. Kobalt or kobold is named from a myth that imps or gremlins lived underground and teased the miners.
metal oxides. Pure corundum is clear in color. The gem colors of corundum are a result of minor metal oxide impurities; ruby is colored by chromium oxide.
to deceive. Phenakite is named from a Greek word for "to deceive" because it was long confused with quartz and other minerals that appear similar. A British specimen, pictured in an 1811 work, was described as white tourmaline for twenty years before it was recognized as a new mineral.
| You're in Philadelphia, visiting the cemetery where old Ben Franklin is buried. You notice that many of the tombstones, which are made out of sandstone, are not in very good condition, and that the writing is hardly legible. You can easily brush loose sand grains out of the rock. One of the docents explains that the deterioration happened when Philadelphia was heavily industrialized, and there were not yet environmental regulations in place about acid rain. Wait-- acid rain is sulfuric acid, which must not be very effective at dissolving SiO2, because it is usually stored in glass containers. What is going on? | Geology Rocks!
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The cement holding the grains together was calcite. The grains in a sandstone can be cemented by any number of minerals, like quartz, calcite, dolomite, kaolinite, chlorite, or others. The cement mineral does not necessarily have to be the same as the mineral the grains are made out of. In this case, a neat explanation for why the sandstone was deteriorating from the acid rain, but the individual grains were still largely intact, would be that the sandstone was cemented by calcite cement, which is not resistant to sulfuric acid. Incidentally, people drilling oil wells will sometimes dump sulfuric acid into the well to dissolve the calcite cement and improve the porosity of the rock, all the better to extract the oil. But, make sure the cement really is calcite, and not chlorite, or else you'll end up with a nasty sludge that clogs all the porosity!
| Once again, you're out hiking with your spouse and kids. You see some gigantic, maybe one meter in diameter, spherical rocks in a sandstone matrix. Your son asks, "Daddy, daddy, what's that?" So you tell him in a very serious and informative tone, "Junior, those are called concretions." He asks, "How did they get there?" You explain that they eroded out, that they were harder than the surrounding sandstone. "No, daddy," Junior says, "Why did they form?"
What do you tell him now? | Geology Rocks!
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They precipitate around a nucleus, sometimes consisting of organic matter. Sometimes concretions form by mineral precipitation around organic material. Sometimes concretions can preserve fossils in exquisite detail! The only problem is getting the fossils out, since the concretions are usually harder than the surrounding rock. Interestingly, in Italy, concretions seem to have religious significance-- there are shrines with concretions topped by crosses, statues of the Virgin Mary, etc.
| A geology quiz would not be a geology quiz without a question about volcanoes. So here it is. You hear about volcanoes like Mount St. Helens or Vesuvius that blow up explosively and destroy everything with floods of burning hot volcanic ash. You also hear about volcanoes, like the Hawaiian volcanoes, that never seem to do that, and contentedly pour out runny lava to the end of their days. What accounts for the difference? | Geology Rocks!
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The composition of the lava. The difference is in the composition of the magma. The "runny" volcanoes like the Hawaiian volcanoes have magma that is rich in iron and magnesium. The word to describe this composition of magma is "mafic." The crystal structure of the minerals in the lava is relatively simple, and is not able to trap much dissolved gas. The "constipated" volcanoes like Mount Saint Helens have "felsic" magma, without the iron and magnesium, which has a very complicated molecular structure, which can trap a lot of dissolved gas. When the pressure builds too much-- BLAM! The pressure from the gas creates a very violent explosion. The magma from mafic and felsic volcanoes produce different rock types, basalt and gabbro for mafic, rhyolite and granite for felsic. Which type of volcano would I rather live near? A mafic one. You still wouldn't find me living near any volcanoes, though...
| It's hard to think about geology without thinking of paleontology, and paleontology without dinosaurs. But your interest in dinosaurs is geological, not biological. You don't want to see dinosaur bones in a museum, you want to see them "in their natural habitat," in the rock matrix! Where would be the best place to do this? | Geology Rocks!
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Dinosaur National Park, Vernal, UT. Once upon a time, there was a sandbar on a river. The river would periodically flood, and wash dinosaur carcasses onto the sandbar. 145 million years later, the place is a sandstone formation containing lots and lots of dinosaur bones. On August 17, 1909, a paleontologist named Earl Douglas discovered this formation, and began excavations. In 1915, the quarry was declared a national monument, and nowadays there is a visitor center on the site. The building backs up against the quarry, and one entire wall is simply the rock with the bones still embedded in the sandstone. It is really quite impressive.
| Dramatic geology statement time: You are walking along an exposure of limestone, and stop to pick up a few fossils of crinoid columnals. What dramatic, attention-grabbing statement can you make? | Geology Rocks!
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This place was underwater about 300 million years ago!. Limestone is only deposited in shallow marine environments. There were no ocean-going dinosaurs: plesiosarus, pliosaurs, and ichthyosaurs were aquatic, but they weren't dinosaurs! Crinoids, also known as sea lilies, flourished maybe 350-250 million years ago, and while most of them went extinct at the end of the Paleozoic, there are still a few species alive today. They look roughly like flowers, but are actually animals related to starfish and sea urchins. Columnals are the hard parts that make up the stem of the crinoid. They look like beads, and are very common in some Paleozoic rocks. You also know that this area had salt water, not fresh water-- crinoids are very intolerant of salinity levels much different from oceanic salinity.
| An "expert" is being interviewed on TV about the recent Mars missions. He says, "Experiments have shown that most of the sand grains on Mars are made up of the mineral olivine. This does not disprove my theory that there were extended periods of liquid water on Mars in the not-too-distant past." Why is this so-called "expert" wrong? | Geology Rocks!
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Olivine weathers very quickly in the presence of water. A geologist named Goldich did a study of the rates of chemical weathering in different minerals. Olivine is one of the minerals which weathers the quickest with exposure to water. It is extremely unlikely that olivine sand would have been around for millions of years in the presence of water. Incidentally, the rate at which minerals weather is inversely proportional to the temperature and pressure at which they crystallize. So, a mineral which crystallizes at a high temperature and pressure weathers quickly, while a mineral which crystallizes at a lower temperature and pressure weathers slowly. Diamonds crystallize at very high temperatures and pressure. A diamond is forever... oops. But if you do want to get your love a long-lasting mineral, get zircon, which is almost as sparkly as diamond, certainly less expensive, and can last up to 4 billion years. Yes, zircon crystals from Western Australia have been measured to be 4.1 to 4.4 billion years old, on par with the estimated age of the crystallization of the Earth. But back to this question. Mars is red because the dust grains are covered with a layer of iron oxide, which is red. And, sand refers the size of a grain of sediment, not the composition, so it is quite possible for sand to be made up of minerals other than quartz. This experiment was really conducted!
| A group of investigators from CSI have heard of your geological superpowers and want your help in solving a crime. The murder happened on a picturesque beach on the island of Hawaii. One of the murder suspects was arrested as he was getting off the plane, claiming to have done his sunbathing only on the picturesque beaches of Hippie Hollow in Austin, TX. You know that Hawaii is made mostly of basalt, and that the Austin area is located in a region of limestone. Black sand was discovered in the suspects' sandals and swimming trunks. Is he lying? | Geology Rocks!
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Yes. This suspect obviously did not know too much about geology. The sand in a limestone area is generally light-colored, and the sand that comes from basalt is dark-colored, nearly black. He's lying! This is a simple example, and lest you think this situation is too unlikely, one of my geology professors was indeed called upon to investigate the origin of some sand found in a suspect's trouser cuff.
| You're out hiking with family and friends when you discover sets of asymmetric ripples in a sandstone. You know that geology is "great at parties! thrill your kids!" material, so what information can you wow them with? | Geology Rocks!
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All of these (The direction of the current, The relative speed of the current, The rate of deposition). An asymmetric ripple (symmetric ones will be considered in a minute) has two different sides: a long side with a shallow slope, the "stoss side," and a shorter side with a steeper slope, the "lee side." The current flows from the stoss to the lee side. Individual sand grains are pushed up the stoss slope to the crest of the ripple, and then cascade down the lee slope. At the bottom of the lee slope, they begin their journey up the stoss slope of the next ripple. Hence, you can tell the direction of the current from a ripple. You can tell the relative speed of the current from the shape of the ripple. Bigger ripples, also called dunes, indicate higher current flow (though the size of the sand grains affect this as well.) But there is also the top view of a ripple to consider: ripples with wavy crests come from higher velocity environments than ripples with straight crests. You can tell the rate of deposition of a ripple from the ratio of how much the ripple grew up to how much crest of the ripple moved over, the "rise over run" from high school algebra. In the case of a symmetric ripple, where you can't tell the stoss slope from the lee slope, it probably formed from wave action.
| A friend is showing you slides from his vacation. One of them is a picture of him standing next to a reddish cross-bedded sandstone, where the individual beds are about three times as tall as he is. "That must have been a really awesome beach!" he says. But you know better. Where did that sand come from, really? | Geology Rocks!
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A desert. Cross-bedding always indicates ripples or dunes. There is a difference between the two-- a ripple is less than 6 cm tall, a dune is greater than 6 cm tall. The height of the beds indicate the height of the dunes, in this case, approximately 20 feet high. Ripples and dunes cannot be higher than the depth of the fluid they form in, so in this case, streams are out. Now, it takes energy to move sediment into ripples and dunes, and it takes more energy (and bigger grain sizes) to form bigger ripples and dunes. It is unlikely there would have been sufficient energy in a calm lagoon. This leaves a beach and a desert. The red color in the sandstone is likely an iron oxide coating on the sand grains, which is only found in desert environments. In fact, this was probably an "erg," an extensive desert area covered by deep sand dunes.
| Sherlock Holmes, who is a geologist in this alternate universe, is going for a walk with his good friend Dr. Watson. They observe a conglomerate in which many of the cobbles are well-rounded and have small chips and fracture marks. Dr. Watson asks, "What was the likely depositional environment of this sediment?" What does Sherlock reply? | Geology Rocks!
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A mountain stream. Sherlock says, "Well, Watson, the large size of the sediment, fist-sized cobbles, indicates that this was not far from the source area. After all, if the cobbles had been transported much further, say to a river delta or all the way out to sea, there would have been time to break them down further. There must also have been some way to transport the cobbles, which, after all, are relatively large. This points to a "high-energy" environment, such as a mountain stream, where the force of gravity on steep slopes would have helped move the rocks, or a glacier. However, we know that it came from a stream because the chips and fractures, known as 'crescentic impact fractures,' are only found in stream environments. Elementary, my dear Watson."
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