# Tag Info

22

Absolutely not. First of all, "rare earth magnet ore", meaning the ores of metals like neodymium (Nd) and samarium (Sm), is not magnetic at all. It only becomes a magnet once you make a magnet out of it. For example, one such magnet is Nd2Fe14B and it only becomes a magnet after neodymium is combined with iron and boron. Naturally occuring neodymium ore ...

18

I'm a volcanologist and I have worked on erupting volcanoes. First of all, volcanologists almost never actually wear those suits. Heat is almost never the hazard that matters in the situations in which we work. The hazards are usually the chance of being hit by ballistics, or getting gassed. The reason you see those suits so often is that they look really ...

13

Let me first correct a small misconception. Where you are talking about 'the magma ocean', you are implying that one exists. This is in fact false. There is no 'magma ocean' in the Earth at the moment (and it has been like that for several billions years). The lavas you see erupting in volcanoes are not coming from a magma ocean. They are coming from either ...

11

No. Cosmic radiation are high-energy particles that create particle showers high up in the terrestrial atmosphere. Those particle shower are heavily beamed downwards, and although in principle some secondary shower products feel the local magnetic fields, effectively are not affected by the natural terrestrial field, let alone weaker local fields. Those ...

11

I think the answer to "Why don't scientists use fire entry suits to study volcanoes?" is that this is a question of professional ethics rather than of technology. For some institution to support, condone, or fund such a proposal, it would first have to conduct some sort of a safety review. At a significant cost, this approach would encourage risky behavior, ...

11

"Rare earth" metals consist of Scandium, Yttrium, and 15 other metals of the so-called "Lanthanide" series toward the bottom of the Periodic Table of elements. Basically, these are the chemicals that we didn't study in chemistry class at school. Like other metals, they have two electrons in the outer shell, but unlike "metallic" chemicals such as sodium or ...

9

Technically yes, but practically, usually no. The magnetic field varies in three dimensions and the variations are not parallel to the Earth's surface. However, horizontal distances varies usually on a larger magnitude than elevation and for everyday use, the declination is only based on horizontal position. The common model for the Earth's magnetic ...

8

Yes, there are maps that map out variations in the earth's magnetic field, example here http://science.gc.ca/eic/site/063.nsf/eng/97358.html. The large variations are primarily due to the presence of ferric materials, ie large deposits of material like magnetite. There are no areas of rare earth magnets as far as I know, given that rare earth magnets are ...

8

What are the rare earths? The rare earths are a group of several elements. The widest definition includes the 15 lanthanides: La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu, and two more elements: Sc and Y. A quick look at the periodic table gives a hint as to why Sc and Y are also considered as REE: (modified from this) I've marked all the ...

7

Geology/Petrology has proposed some models for the origin of basalts which are based upon chemical evidence from rocks. Modern origin-models have been constrained by isotopic chemistry for some time. I do not claim to be current in this subject, but I believe the conclusions in this classic paper are still accepted as the most likely origin models. Models ...

7

Perhaps they are called Igneous Petrologists ? Someone who studies magma/lava flows tends to go by Geophysicist because they inherently study continuum mechanics and fluid flow.

5

Short answer Na and K are incompatible in the mantle. Low degree melting that occurs deep in the mantle forms magmas enriched in Na and K. Magmas formed due to hot spots are formed deep in the mantle. Long answer Tholeiitic basalts are voluminous magmas that form due to decompression of mantle rocks. The mantle then melts to a rather large degree at low ...

4

Felsic magmas contain much more silica (SiO2) than mafic magmas (almost by definition). The excess silica chains cause the magma to be much more viscous and therefore more prone to explosive eruptions (they trap gas and require high pressures to flow). This is why felsic magmas produce crazy explosive pyroclastic flows (forming ignimbrite) and very mafic ...

4

Main difference between a subvolcanic verses a plutonic is depth at which the rock solidified at from its molten state. Plutonic implies a depth greater than subvolcanic by definition but I am sure there is some overlap between shallow end of plutonic and subvolcanic. Depth of emplacement for plutonic would mostly be much greater than 2 km. Plutonic is ...

4

It does seem like it's impossible to know unless you have additional information. However, I think there is a hint in there. See this white halo around the intrusion? My guess (and I could be wrong here) is that it's not there for artistic reasons but rather it's there to provide a very strong hint. My feeling that this is some kind of metamorphosed contact ...

4

Yes, they are. It's not the sills or dykes that "jump", it's the magma. Depending on the various parameters such as viscosity, stress, temperature, pressure, and local conditions and availability of joints, the magma will flow either as a sill or a dyke (or some other intrusive body). Notice that your two sketches are basically the same thing - it's just ...

4

In the early stages of crystallization, the ions that form high-temperature minerals are depleted from the melt. Rare ions that do not participate in the crystallization of common rock-forming minerals become concentrated in the melt and in the excluded water. These ions can form the rare minerals that are often found in pegmatites... rare elements ...

3

Main danger to life near a volcano is not heat from the lava but volcanic gases. Volcanic gases are typically very acidic, poisonous gases and can displace breathable air near lava flows. http://volcanoes.usgs.gov/hazards/gas/ http://en.wikipedia.org/wiki/Volcanic_gas

3

Melting lunar dust of basaltic composition will result (unsurprisingly) in basalt lava. There might be some volatile loss - if for some reason the basalt had some H2O or CO2 trapped in the solid you will most likely lose it. It's probably not going to change its chemical properties much though. On Earth, as lava cools down fast, for example when it's ...

3

I've already commented on this before here. This will not work regardless of whether this is iron or lead or anything else. The fact that it was published in Nature does not mean it is true, always remember that. A 108 kg ball of iron would have about 30 metres in diameter, which is not a lot, compared to Earth scales. Here is why it will not work: We ...

2

The magnetic field stops the charged particles mostly by trapping them along their fields lines (globally parallel to the ground at most latitudes, plunging to the ground near the poles (therefore allowing northern lights). If you 1up nature and build a massive electromagnet, you could at most create a secondary pole, which would act as particle channel to ...

2

Although the other answers have correctly pointed out that this isn't a relevant thing on Earth, it should be mentioned that such an effect does occur on the Moon: it is the likely cause for the Lunar swirls. These are though to be the result of magnetic anomalies causing local shielding of the surface from solar wind. This effect prevents the regions from ...

2

Magnetite is a type of iron ore and does not significantly affect the Earth's magnetic field. It would not protect you from cosmic radiation. However, cosmic radiation is more intense high in the atmosphere, so airline cabin crew and people living on high mountains are slightly more at risk. If you are worried about how to avoid radiation damage, the thing ...

2

What's happening is called induced magnetism, detailed in a variety of places, including this paper by Kostadinova-Avramova and Kovacheva in Geophysical Journal International: It is well established that baked clays, when cooling from temperatures around 700 °C in a weak magnetic field, such as that of the Earth, acquire a thermoremanent magnetization ...

2

This answer is based on Winter's presentation for his textbook. Look up chapter 7 on his website, and start at slide 39. First let's go through some of your statements: Felsic magmas crystallise in the crust, unlike mafic magmas which tend to make it to the Earth's surface Not necessarily. It is true the upper continental crust is composed mostly of ...

2

Of course there is, and in not that complex. Is called the heat equation, and is a type of diffusion equation that can be easily solved numerically or analytically in some simple geometries. If you don't want to get involved in the math, you can use one of mane heat transfer simulation software, there are even online version that run in your browser like ...

2

You might get a lava seepage, but I doubt it. The cross-sectional area of a borehole is small compared to the total cross sectional area of fractures that are there already. Note that volcanoes bulge quite markedly due to lava up-welling and deformation due to magma pressure, so the volcano is invariably well fractured. A small hole is likely to fill up with ...

2

It's both. The rocks above the sill go up, whereas those below it go down. For shallow diking events it's mostly up. This is all based on theory of linear elasticity. People model deformation using elasticity all the time, especially for studying deformation at volcanoes which one can measure using GPS, leveling, InSAR, etc.

1

From McKenzie's original 1984 paper and from Spiegelman & McKenzie (1987) paper the equations that govern the conservation of momentum and mass of a low-viscosity fluid melt (magma) in a deformable matrix (rocks) are: ${\partial\over\partial t} (\rho_f\phi) + \nabla \cdot (\rho_f\phi{\bf v})=\Gamma$ \${\partial\over\partial t} [\rho_s(1-\phi)] + \nabla \...

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