Does any one know what two minerals compose most of the world's sand?
469041
Quartz & Feldspar make up most of the abiogenic sands (eroded from rocks).\n\nActually silica (silicon dioxide) & quartz are the same thing.\n\nThe other is feldspar which usually breaks down into clay depending upon the right surface conditions (wet/humid).
925717
There is a big problem with "how big is a grain of sand?".  Sand is defined as having grains from 1/16 millimetre in diameter to 2 millimetres, a huge factor in volume.\n\nHalf a millimetre is the boundary between "medium" and "coarse" sand.  One such grain would weigh a five-thousandth of a gram, and based on a whole series of "average" or "typical" figure for other properties, it could reasonably be estimated to contain about 8 * 10^17 molecules.\n\n8 * 10^17 grains of that size spread out 1 foot deep would only occupy an area about 9 miles by 9 miles.  I think that all the beaches on earth should beat that quite handily.  However, if you choose the very coarsest sand, it goes up by 64 times as many molecules then 64 times as many of those grains, making about  600 miles by 600 miles which needs a bit more thinking about.  I think the beaches still win, but it's not as obvious.
34438
Sand was not invented.  It was created naturally by waves or other force erroding pieces of quartz (a rock) and making it smaller.
843681
Si is the most abundant mineral element, but feldspar would be the most abundant mineral as far as rocks & minerals. Quartz comes in second.
661217
•     Calcium\n•     Phosphorus\n•     Sodium\n•     Chlorine\n•     Potassium\n•     Magnesium\n•     Sulfur\n\nAre all macrominerals, so out of your choices, only Ca and Cl.
165682
A complete answer to this question would require a very large book.  You will need better focus for a short answer.\n\nAcids dissolve most minerals and rocks.  Even water dissolves rocks or rock constituents over a long period of time.  There is fabulous erosion in calcium rich rocks creating tunnels and underground chambers...\n\nAcid rain enhances this process greatly.  Virtually all the salts in the oceans came by the erosion of rock salts over aeons of time spent under the never ceasing rainy seasons.\n\nSome conditions are rock forming or metamorphosing, others are rock dissolving.\n\nHeat and cold are also factors in the deterioration of rock, making it more vulnerable to water and acid rain.\n\nThere are many fabulous websites on rocks and minerals and gemstones.  Just Google some of that and you will pull up two or three super-excellent ones.\n\nTry also Googling "rock geological processes."  Keep it in quotes.
480536
should be glass. unless in its original form of sand than should be water. Remember Super-man made that huge piece of glass to reflect the sun an blind those crazy alien people!
1185112
Here is the boring wikipedia answer, there is another specific answer for California beach sand at the end:\n\nSand is an example of a class of materials called granular matter. Sand is a naturally occurring, finely divided rock, comprising particles or granules ranging in size from 0.0625 (or 1/16) to 2 millimeters. An individual particle in this range size is termed a sand grain. The next smaller size class in geology is silt: particles below 0.0625 mm down to 0.004 mm in size. The next larger size class above sand is gravel, with particles ranging from 2 mm up to 64 mm (see grain size for standards in use). Sand feels gritty when rubbed between your fingers (silt feels like flour).\n\n\nThe most common constituent of sand in inland continental settings and non-tropical coastal settings is silica (silicon dioxide), usually in the form of quartz which because of its chemical inertness and considerable hardness is quite resistant to weathering. However, the composition of sand varies according to local rock sources and conditions. The bright white sands found in tropical and subtropical coastal settings are ground-up limestone. Arkose is a sand or sandstone with considerable feldspar content which is derived from the weathering and erosion of a usually nearby granite. Some locations have sands that contain magnetite, chlorite, glauconite, or gypsum. Sands rich in magnetite are dark to black in color, as are sands derived from volcanic basalts. The chlorite-glauconite bearing sands are typically green in color, as are sands derived from basalts (lavas) with a high olivine content. The gypsum sand dunes of the White Sands National Monument in New Mexico are famous for their bright, white color. Sand deposits in some areas contain garnets and other resistant minerals, including some small gemstones.\n\nHere's another specific answer for California:\n\nBeaches vary in color according to the mineral content of the sand, which is also a clue to the origin to the eroded sediments that make up the sand supply. eroded shale cliffs create the charcoal gray beach sand at Shelter Cove in Humboldt County. North of Humboldt Bay, the coarse sands of Agate Beach are multicolored agates that have been ground and polished by the surf. Ground quartz and feldspar mineral make up the white beaches of Carmel, while a few miles to the north in Sand City, amber colored sand indicates the presence of iron mineral. Close inspection reveals that white sand beaches are mosaic of pale quartz grains, pink green or white feldspar and fleck o black mica.
1062405
silica is basically sand. it is a oxide of silicon (SiO2) ie. silicon dioxide
897089
Well believe it or not it is the composition of the two. \ncontinental crust is "typically" silicic, meaning it is composed largely of silica rich minerals, oceanic crust is more commonly "mafic" meaning it is composed of minerals with abundant Iron and Magnesium.  This oceanic crust is heavier.\nBecause of this the continental crusts are "floating" higher than the oceanic crusts.  When the two converge (i.e. along the west coast of south america for example) typically the lower oceanic crust is subducted beneath the continental crust..\nCool huh
123869
How many grains of sand are there on a beach?\n\nSomething like that.
605599
A mineral is a naturally occurring, inorganic solid with a definite chemical composition and a crystalline structure. A rock is an aggregate of one or more minerals. (A rock may also include organic remains.) Some rocks are predominantly composed of just one mineral. For example, limestone is a sedimentary rock composed almost entirely of the mineral calcite. Other rocks contain many minerals, and the specific minerals in a rock can vary widely. Some minerals, like quartz, mica or feldspar are common, while others have been found in only one or two locations worldwide. Over half of the mineral species known are so rare that they have only been found in a handful of samples, and many are known from only one or two small grains.\nthere for its hard to say which is rarest.
104128
Wind is the primary force that creates sand dunes. Sand itself is generally created by the erosion of rock material by water and ice.\n\nThere are two types of movement that wind causes in sand. One is called saltation. Wind picks up grains of sand and gives them forward momentum, but they will often fall back and bounce repeatedly, or cause other grains to move. This is about 75% of all movement of sand to form dunes. \n\nThe other movement method is called surface creep. Surface creep is the process where heavier sand grains are moved forward along a surface as saltating grains strike them.  It is estimated that about 25% of sand movement is moved this way. \n\nAs this moving sand encounters obstacles or changes in elevation such as a basin, the irregular flow of the wind will cause sand to accumulate in the "wind shadows." However, obstacles are not necessary to make dunes. The bouncing sand grains will gradually slow, losing energy from impacting heavier grains, and the sand itself tends to slow the wind speed close to the ground. Together, this differential speed of motion among grains, and saltation drag on the wind, will begin to produce small piles of sand, or ripples. Larger grains will tend to accumulate because the wind cannot move them, and cause more ripple effects.\n\nTrue dunes are formed when relatively strong winds blow over fine grained sands. The coarser grains tend to stabilize the windward surface of the dune, and finer grains are moved by saltation upward and over the peak of the dune, where they fall out of the wind and slip downward. \n\nIn areas of active dunes the dunes will migrate in the direction of the wind over periods of years. Many of the largest sand dunes in the world are considered paleodunes that are no longer moving. \n\nTo read more about sand dunes and how they form, as well as some information on the different types of sand dunes go here:\nhttp://www.nps.gov/whsa/Sand%20Dune%20Geology.htm
707824
I don't know but if you click on the site below you'll find out real quick. They know minerals.
788400
quartz. This is not all that magma contains though, It can also have feldspar, garnet, and many other minerals. Quartz is the most common though.
828414
We are dealing with an illusion caused by grain size and moisture content here.  In fact sand is quite hard because it is made up of individual rock and mineral grains.  Limestone and quartz are pretty hard materials.  If a sand is damp, or has very small rounded grains, it can feel soft to the hand however.\n\nClays on the other hand are soft because they are created by the chemical weathering of other minerals (such as pyroxene or feldspar) and the individual clay units are microscopic in size.  Clays usually contain a high proportion of water in their structure as well (it can be as high as 70%).\n\nWhen a geologist in the field can't make out the whether a rock is a siltstone (clastic) or clay (chemical) because the grain sizes are too small to see, a simple test is to break off a small fragment put it between ones teeth.  If its chewy and soft, its a clay.  If its hard and gritty, its a silt. \n(Warning - experts only folks.  Some rocks contain poisonous minerals so don't go around randomly tasting rocks.)
299488
Agate & Quartz are both composed of SiO2 or silicon dioxide.\n\nAgate is a cryptocrystalline version of quartz.(very small, as not to be seen with the naked eye, crystals) \n\nAgate is formed in sedimentary deposits from dissolved quartz that is redeposited. This is usually near the surface where there is lower pressure & temperatures.\n\nMany times agate is found as geodes. These are really cool. Sometimes they fill in completely w/ layers of silica. Other minerals may be present as to make color bands. Other times the geode will not fill completely in before crystals start forming. WOW! Love these!\n\nSometimes from the process mentioned above, cryptocrystalline silica will seep into bones & remnants of tree trunks. Ever seen petrified wood? OF course this is not the only mineral that will do this in wood & bones.\n\nOpals are also a variety of quartz. It contains minute amounts of water in its structure. The only difference here is that opals are amorphous meaning that there are no crystals.\n\nSilicon Dioxide is the most abundant mineral in the earth's crust. It is found everywhere and in all kinds of forms.\n\n:)