why are gems and ores different?
116210
A gem is a pure or near pure crystalline form above a certain size useds for decoration or jewelry, where the ore is a mixture of many minerals, crystalline or not, where none of the forms are large enough to be a gem.  The word gem is a subjective term.
881405
1. A diamond is a specific type of crystal form of Carbon (contrary to what some people say and what some have answered:  a diamond was NEVER coal -- the only similarity is that they both contain carbon.)\n2. You cannot "make" a diamond out of a crystal.\n3. You can try to cut a crystal to maybe resemble a cut diamond, but no one would ever confuse the two.\n4. Crystals have certain alignments of the crystal facies along which the crystal will split -- it is along these facies that an expert will "cut" a crystal to get a specific shape.
255970
Iron pyrite is often found in the same mineral environment as real gold. The differece  to the prospector is the weigh. When panning, the pyrite will leave the pan as the much heavier gold settles to the bottom. Pyrite is brittle and will form crystals, gold usually doesn't. If you have a large enough piece, you can scratch it and it will have a sulfurish smell.
552288
rocks are made up of minerals
825778
diamonds exhibit rare beauty because of its characteristics (very high index of refraction) and every woman wants one. (diamonds ara a girl's best friend, but not mine hehe)\ndemand of the market.\ndiamonds are not found easily.\ndiamonds are hard (to cut and polish)\nand because the first one who saw a diamond thought he could make a lot of money.\n\nactually, you can grow or make your own diamond out of coal (yup...carbon)\nbut you'll have to be millions of years old to already own one...
1055512
Ruby is the mineral Corundum  ( Aluminum oxide) \n\nGarnet is a Silicate ( Silicon oxide) SiO4\n\nSapphires are all colors but RED. Red Corundum is called Ruby.\nPink is sometimes called pink sapphire or pink ruby.\n\nGarnets come in all color but blue. But blue can be made.\n\nTo me the Garnet is a brighter red and more crystalline; but there are many beautiful orange and green garnets.
244879
Minerals are made up of combinations of elements & rocks are made up of combinations of minerals.\n\nTechnically a rock & a mineral are not the same thing.\n\nSince minerals make up rocks I guess they have that same thing in common.
78252
If I remember correctly from my science classes, a mineral is essentially a solid substance that has a crystal structure.  (That's two right there - It's solid, and has to be crystal in structure.)  It also has to be inorganic and occurs naturally, and also homogenous.  Not to mention the fact that it's supposed to have a defined chemical composition.  That's more than four characteristics, but I believe them to be all true of minerals....
666767
Quartz itself does not contain metal. Quartz is a crystal. What you've found is not pure quartz if a metal detector is picking it up. It's mixed with a metal, and that could be anything, depending on where you live. It's probably iron, since that's a pretty common metal to find lying around (not in a pure form, of course).\nBut go ahead and smash them apart if you feel like it.  You might just find some reddish stuff (iron) or maybe you've gotten lucky and managed to find some quartz that fused with gold or something.
246934
A crystal is a type of structure. What makes something diamond, sapphire, quartz, etc, is its chemical composition.
1182912
msneed took their answer straight from wikipedia off the internet.  The one thing that needs to be mentioned is that pure gold is 24 karat, but 24 karat is too soft for most jewelry applications.  Therefore most jewelry is either 10, 12, 14 or 18 karat.  This means that most all gold jewelry is mixed with either Copper, nickel, zinc, and/or silver.  White gold usually has much more silver and sometimes palladium or rhodium, therefore white gold is more expensive at the same weight as a normal gold item because white gold has more precious metals in its contents.
993033
check this:\nhttp://www.gemstone.org/gem-by-gem/gem-by-gem.html
14822
That's like asking how long is a piece of rope. Sapphires come in all shapes and sizes and are typically measured in karats just like diamonds or any other precious gemstone.
860456
Rock can be either. For example, gold can be included in quartzite as discrete nuggets and therefore is heterogeneous but in shales and slates, lava, and even crystals, it is homogeneous. A heterogeneous material is a mixture of two or more things that are not bonded together and could be separated easily. A homogeneous substance is one where two or more elements are joined together in such a way that they are not easily separated. Think of this...sand and sugar...they are heterogeneous as we can dissolve the sugar and separate them easily, but with milk and coffee...they are homogeneous as it would be very difficult to divide the two.
900927
Well, in things like pegmitites, late stage crystalized rocks, you can have very high amounts of incompatable elements, like Li, Au, Ag, B, Zr, and many more.  That's why you get minerals like beryl, lepidolite, tourmaline, etc.
195772
Different locations = different soil and rock...\n\nDifferent soil and rock = different minerals dissolved in surface water...\n\nDifferent minerals disolved in surface water = different pH.\n\n(Yo Jargan:  "Geometric"???  Try Geographic...)
606550
"A mineral is an element or chemical compound that is normally crystalline and that has been formed as a result of geological processes" (Nickel, E. H., 1995).\n\nA rock can be composed of lots of different minerals