why do some rocks glow?
351628
They glow if they contain fluoresent substance(s) such as phosphorus compounds.
326387
Through the processes of weathering, erosion, deposition, sedimentation, cementation, & lithification an igneous rock can become sedimentary.\n\nIgneous rock can be weathered by one of two processes. The first is mechanical weathering. This would include things like the freeze/thaw cycles. Water entering into tiny cracks in rock will freeze causing the crack to expand. There is a larger gap left when the ice melts. Some types of igneous rock will also exfoliate. As they emerge to the surface through uplifting, they will expand (due to less pressure). Sheets of rock will literally peel off from the rock's surface and fall at the base of the rock.\n\nThe other is chemical weathering. This is usually b/c of water's interaction w/ the minerals in the rock. One type of mineral will break down into another more stable one.\n\nThis weathered rock can erode & be transported elsewhere where it is deposited as sediment.\n\nMany layers of sediment may be placed down. Pressure from the layers above cause the water & air in the sediment layers below to be squeezed out.\n\nPressure from above, along w/ dissolved minerals left behind from the water, can cause lithification & cementation to occur.\n\nThese processes take quite some time to occur.
247030
thats an igneoous rock. dont know where to get one though
708140
We do glow, but not with a frequency that the human eye can see. If you look at the human body with an infrared camera you will see the heat glow.
129822
You've been given exhaustive lists, copied directly from websites without giving proper citation I imagine. \n\nHere is how to think about this question so that you can recall and understand the answer, without just memorizing a bunch of rock names.\n\nUse the rock cycle. Igneous rocks are of two groups, those formed within the earth and those formed by volcanism.  The volcanic rocks will show signs of that volcanism and will be things like black columnar basalt found in massive flows. Obsidian (volcanic glass) that flowed as liquid, scoria and pumice which are like foam because the dissolved gases expanded and made them bubble as they hardened. The other igneous group formed under the earth's surface, and includes things like granite where you can see the crystals that formed as it cooled and solidified. \n\nSedimentary rocks are also in two major informal groups (and a minor third). The first group of sedimentary rocks is clastics. These are formed by weathering, transport and deposition. Weatherings breaks down rocks like igneous, metamorphic and even sedimentary rocks and transport by wind, water, or gravity deposits these rocks as accumulations of clasts, (thus clastics). They become sandstone, shale, and conglomerate. The other major sedimentary group is carbonates. These rocks are 'born' because they are formed by living things. Ocean environments (and lakes too) have many organisms that make shells, corals that make reefs, and algae that make fine carbonate sediments (known as carbonate mud). Even bacteria get into the act helping to precipitate carbonates in many ocean environments. The third group of sedimentary rocks is those that are dissolved by water and deposited by evaporation or precipitation. These include gypsum, halite, sylvite, and many more. \n\nMetamorphic rocks all start life as one of the previous groups. You can metamorphose a granite into a granitic gneiss by burial, pressure and heat. You can metamorphose a basalt into an amphibolite. You can make limestone into marble. Sandstone turns into quartzite.\n\nRemember the rock cycle, associate the rocks as they move through it, and you won't have trouble remembering examples of rock types. Also don’t get tripped up by the difference between a mineral and a rock. Geologists sometimes use the two terms identically, but there is a formal difference between a rock (which is an impure mixture) and a mineral that is chemically consistent.
210093
Deep within the Earth it is so hot that some rocks slowly melt and become a thick flowing substance called magma. Because it is lighter than the solid rock around it, magma rises and collects in magma chambers. Eventually some of the magma pushes through vents and fissures in the Earth's surface. A volcanic eruption occurs! Magma that has erupted is called lava. \n\nalso\n\nWhen rock inside the Earth becomes hot enough it melts.\nThis molten rock, or magma, is less dense than the surrounding\nsolid rock.  Just as an object that is less dense than\nwater will float on water, the relatively low density of\nthe magma causes it to rise to the surface of the Earth.\n \nIf the magma contains water and dissolved gasses, when\nthe magma reaches the surface the water and dissolved\ngasses will suddenly expand into steam and gas, causing\na violent eruption.  This is like shaking a coke\ncan and then popping the tab.
143382
On the ice, there are really tiny mounds of ice called pebble, so essentially the rock is gliding on this pebble, and curls because of the way the bottom of the rock contacts the pebble. When you sweep, you are melting these ice droplets and the little amount of moisture/water make the rock glide farther, but it also holds the rock straighter. However, if you sweep once the rock has caught the pebble and has begun to curl, it will make it continue curling in that direction.
172643
Check this out: http://en.wikipedia.org/wiki/Moon_rocks
58331
Igneous rocks are formed with heat. They are most commonly found around volcanoes. Metamorphic rocks are formed with heat and pressure. Sedimentary rocks, like sandstone and limestone, are formed by pressure.
712767
"Glow in the dark" items have in them a substance that's slightly radioactive. The "phosphorescence" is a reaction of this substance with any amount of projected photons, or light. As the light passes through this substance, it acts as an irritant through this substance like a bunch of pebbles on a pond, only in THIS pond the pebbles bounce off of each other and the reactant until they're completely out of it. Hence the slow fading. Eventually, it's "glow in the dark" properties will diminish.
786689
Sedimentary rocks are formed at the surface of the Earth, either in water or on land. They are layered accumulations of sediments: fragments of rocks, minerals, or animal or plant material. Temperatures and pressures are low at the Earth's surface, and sedimentary rocks show this fact by their appearance and the minerals they contain. Most sedimentary rocks become cemented together by minerals and chemicals or are held together by electrical attraction; some, however, remain loose and unconsolidated. The layers are normally parallel or nearly parallel to the Earth's surface; if they are at high angles to the surface or are twisted or broken, some kind of Earth movement has occurred since the rock was formed. Sedimentary rocks are forming around us all the time. Sand and gravel on beaches or in river bars look like the sandstone and conglomerate they will become. Compacted and dried mud flats harden into shale. Scuba divers who have seen mud and shells settling on the floors of lagoons find it easy to understand how sedimentary rocks form. \n\nExamples:\n\nArkose \nBreccia \nChalk \nChert \nClaystone \nCoal \nConglomerate \nCoquina \nDolomite \nEvaporite \nGreywacke \nLimestone \nMarl \nMudstone \nOolite \nSandstone \nShale \nSiltstone \n\nFor more check :\n\nhttp://interactive2.usgs.gov/learningweb/explorer/topic_rocks_sedimentary.htm\n\nhttp://en.wikipedia.org/wiki/Sedimentary_rocks\n\nhttp://en.wikipedia.org/wiki/List_of_rocks
502744
Actually, the colour of the glow does not depend on the material filled in the discharge tube. Rather it depends on the material of the discharge tube. So if the discharge tube is made of glass, the glow is somewhat greenish
124066
Anything that isn't flat black can be said to illuminate in the sense that it returns some of the incident light.\nSpecial forms of illumination include light "storage" and fluorescence.\n\nLight storing materials enter an excited state when hit by light and gradually dissipate the excitation as light emission; cadmium sulfide is an example.\n(Later correction: calcium, not cadmium, sulfide.\n\nFluorescence, e.g. fluorescent dyes and the coating on the inside of fluorescent lamps, are excited by incident light (typically ultraviolet) and immediately release the energy as visible light.\n\nLater: Elements, yes.  Think of rare-gas lasers (argon, xenon).
934420
weathering of rocks due to wind,flowing water
159810
Don't be ridiculous, radioactive stuff doesn't glow. However, Hollywood screenwriters think it does. \n\nIn some instances high-energy radioactive particles will cause other stuff to glow, but that's an exception, not the rule. On old radium watch dials the radioactivity from the radium would cause zinc sulfide to fluoresce, but you cannot see the radioactive particles themselves. Radium by itself will not "glow green" and you cannot see electrons or alpha particles unless they react with something (e.g. the phosphor screens in oscilloscopes).
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3 basic types of rocks\n\nIgneous Rocks-Igneous rocks are crystalline solids which form directly from the cooling of magma. This is an exothermic process (it loses heat) and involves a phase change from the liquid to the solid state. The earth is made of igneous rock - at least at the surface where our planet is exposed to the coldness of space. Igneous rocks are given names based upon two things: composition (what they are made of) and texture (how big the crystals are).\n\nSedimentary Rocks-In most places on the surface, the igneous rocks which make up the majority of the crust are covered by a thin veneer of loose sediment, and the rock which is made as layers of this debris get compacted and cemented together. Sedimentary rocks are called secondary, because they are often the result of the accumulation of small pieces broken off of pre-existing rocks. There are three main types of sedimentary rocks:\n\nMetamorphic Rocks-The metamorphics get their name from "meta" (change) and "morph" (form). Any rock can become a metamorphic rock. All that is required is for the rock to be moved into an environment in which the minerals which make up the rock become unstable and out of equilibrium with the new environmental conditions. In most cases, this involves burial which leads to a rise in temperature and pressure. The metamorphic changes in the minerals always move in a direction designed to restore equilibrium. Common metamorphic rocks include slate, schist, gneiss, and marble.
185819
X-rays can cause certain phosphors to fluoresce.