how hydrothermal apatite distinguished from magmatic one?
450378
glycerin content is elevated in the subdeural layer of the hydrothermal as opposed to the orifice
936761
It is a sheet silicate, with one cleavage, and a hardness of one.  Found almost exclusively in metamorphic rocks.
3614
WHICH metamorphic rocks?  It will vary depending on the "ingredient" rocks and HOW they are metamorphing (pressure, heat, both pressure and heat)
312225
The process as a whole is known as 'continental drift,' or 'plate tectonics'. This process is further divided into several processes: divergence, or where plates are moving away from one another as a result of lava welling up and cooling in a mid-ocean ridge; convergence, where two plates collide and either form mountains or subduct depending on their types; and transformance, where tow plates move at opposite directions parallel to one another. \n\nKnowing this, your question can be answered. You are describing convergance between either two oceanic plates or one oceanic plate + one continental plate. The process is also known as subduction, and can form large mountains and volcanic/seismic activity.
853307
It is most likely a schist due to the foliation, mineral alignment and the lack of banding, but pyroxene is most likely to occur in a gneiss so it is probably a high metamorphic grade schist
904334
A dormant volcano no longer erupts regularly but has lava in the batholith and is capable of erupting.  An extinct volcano contains no magma and the batholith has hardened.  It cannot erupt.
82209
Basically one of three ways. These are extrusion, intrusion, and accretion. \n\nExtrusion is the process of volcanism. Volcanoes erupt molten rock that may have originated as subducted oceanic crust or deeper rock. This magma adds huge volumes of rock to the crust as it erupts and cools into solid rock. \n\nIntrusion is a similar process, but no eruption takes place. Large bodies of molten rock float upward over long time periods through the crust. When these cool and harden they are called plutons or batholiths (depending on size-batholiths are larger). These form large parts of the crust.\n\nAccretion is the other method. In some instances plate tectonics can force oceanic plates up and over continental plates. These often form what are called ophiolites where we can examine oceanic crust on dry land. Large parts of continents or islands are often forced against continental plates. This can force sediments and oceanic crust upward creating what are called 'accretionary terrane'. Much of California is an accretionary terrane, built of islands in a fore arc subduction zone that were forced up against a paleocoastline that once was near the eastern border of present day California. \n\nHere two other explanations similar to my own that illustrate these processes:\nhttp://www.physicalgeography.net/fundamentals/10j.html\nhttp://earth.leeds.ac.uk/assyntgeology/extra_info/ehistory.htm
839321
The mechanisms of tectonic plate movement is quite complex, but in its simplest terms, tectonic plates float on molten magma of the earth's interior. Convection currents within the molten magma behave similarly to convection currents in a pan of water being heated on the stove. Water on the bottom of the pan is heated and begins to rise because it is slightly less dense than the cooler water on the top. The cooler is slightly more dense and begins to sink. As this water is heated, it begins to rise, thus a convection movement or convection current is created in the water in the pan. \n\nMagma is far more dense than water and is much hotter, but it is still a fluid. Magma near the core is hotter than the magma beneath the crust. Hotter magma moves up, cooler magma moves down, very very very slowly, but none the less, it moves. The crust, a.k.a. tectonic plates float on the magma. Float some pieces of Styrofoam on the water in the pan. What happens? The foam moves around by the convection forces in the water.  Tectonic plates do the same thing. Its just not as fast.\n\nHope this helps.
400219
Well, it won't be easy.  The two differ only in one way: Spessatite has Mn, while Hessonite (which is a subtype of grossular) has Ca.  The colours are also similar: Spessatite is ususally deep red but may also be black to orange, dark pink, or brown.  Grossular/Hessonite is more likely to be nearly colourless to green, yellow, pink, or brown.\n\nThe best way to tell them apart may be by the assemblage in which they occur.  Hessonite tends to be more commonly associated with skarns and other metamorphosed carbonate-bearing rocks, and is usually associated with calcite, dolomite, wollastonite, tremolite, and epidote.  Spessatite on the other hand tends to more commonly occur in granites, pegmatites, and other felsic igneous rocks, and in Mn-rich metamorphic rocks.\n\nThe only sure way to tell though would be to put them on a microprobe to find out.\n\nGood luck!
105777
I'm going to turn to Wikipedia's definition of a mineral first because I like it (I quote)\n\n"To be classified as a "true" mineral, a substance must be a solid and have a crystal structure. It must also be an inorganic, naturally-occurring, homogenous substance with a defined chemical composition.”\n\nWhat does this mean in terms of your question? There are countless different physical properties of minerals, but you must understand that a couple of key things make a mineral fit the definition. It must be inorganic (Encarta is just wrong here- petroleum and coal are not minerals in any sense and are organic compounds that came from living organisms) . It must have a consistent and homogenous chemical structure (another reason coal and oil don't qualify). It must be naturally occurring. Chemists can make lots of compounds in the laboratory that don't occur naturally. So the most important properties are the chemical composition which must not be a mixture (like a rock has). Obsidian has a consistent chemical structure but because it has no crystal structure it is considered a mineraloid, not a mineral. Cristobalite crystals may occur within obsidian, and cristobalite is thus considered a mineral. Another example of how crystal structure determines a mineral is to compare calcite and aragonite. Both have the exact same chemical formula, calcium carbonate. Because they have different crystal structures they are different minerals. \n\nSo the short answer:\n1. inorganic\n2. crystal structure \n3. chemical homogeneity\n4. naturally occurring\n5. solid
598947
1st answerer is good on location.  Difference between the types are due to the composition of the lava and where they occur.\n\nShield volcanoes, such as those found in Hawaii, have magma that is very low in silica, high in basalt (often referred to as "basaltic" volcanoes).  This means that the lava flows easily, instead of exploding.  That is why there is not a steep slope to the volcano and the biggest threat is just to remain out of the lavas way.\n\nStrato-volcanoes (Mt. St Helens) are found in subduction zones and produce a lava that is described as Andesitic (named after the Andes Mountains in South America).  This lava is high in Silica, which makes it much more viscous, and therefore, more explosive.  This explosiviness defines the shape of the cone, with much steeper sides.  With these types of volcanoes you have the explosive lava threat, but you are also threatened by pyro-clastic flows, and lahars.\n\nCinder cones are the same, compositionally as strato-volcanoes, but are not always located in a subduction zone, and are usually quite alot smaller.
381199
that'll be chalcedony. it differs from quatrz in it's shape, as it usually occurs in botryoidal masses, whereas quartz occurs more in hexagonal prisms. chalcedony is similar to opal, but can be distinguished by its higher specific gravity. it can be formed as a dehydration product of opal, hence the connection. the colour is highly variable, as it can be white, blue, red, green, brown or black, and varieties of chalcedony include jasper, agate, chrysoprase, onyx and carnelian. it's formed in rock cavities, especially lavas, and it develops at relatively low temperatures, whereas quartz occurs in any rock type, and usually formed at higher temperatures
523806
viscous felsic or high silica magmas
65413
I am not going to pick any of those choices because I don't believe any of those are correct, including streak. What you are describing is crystal structure, which might be related to color and streak, but since trace impurities in a mineral often determine color, and streak is nothing more than the color of a powdered form of the mineral I don't think It will be determined by atomic structure with certainty.  Most streaks are white!\n\nCleavage would be a correct answer but it was not included above. Cleavage and crystal structure are closely related properties. \n\nWhat you have described is the crystal structure. All minerals can be classified within 14 basic crystal lattice arrangements of the atoms in three dimensions. These 14 lattice arrangements fit within 7 larger crystal systems, allowing the classification of atomic structure of all known minerals.  To see diagrams of these go here:\nhttp://en.wikipedia.org/wiki/Crystal_structure
230570
Mafic lava is very hot and flows easily it contains less silica and are enriched in iron (Fe), magnesium (Mg), and calcium (Ca) and just encase your trying to get a homework answer I will leave it at that if not you will know what I mean ;)
975135
One way to distinguish between intrusive and extrusive igneous rocks is to observe the crystal size.\nRocks formed below groung (intrusive) have must longer to cool, resulting in a larger crystal size.\nOn the other hand, rocks formed above ground (extrusive) have a much smaller crystal size
341583
They're igneous (made by cooling magma), metamorphic (heat/pressure/chemical change), or sedimentary/stratified (compressed layers).