Spinel has which crystal system?
958993
Like diamonds and garnets, spinel belongs to the isometric or cubic crystal system.  The typical crystal habit of spinels is octahedral - which looks like two 4-sided pyramids placed base to base.  It is also commonly found twinned, and may be found as rhombic dodecahedrons.
19979
Well the lattices in the ionic compounds are formed by two spiecies. The cations and the anions. These being oppositely charged attract each other with a great magnitude of force. \n\nNa+  Cl-  Na+\nCl-  Na+  Cl-\nNa+  Cl-  Na+\n\n    but in metals the Metals are all arranged in a lattice. In this lattice the metal kernels(inner electrons not includeing valence electrons and the nucleus) that are positively charged are all arranged in space. The electrons move freely in the lattice spaces. These hold up the metal kernels together. They move around in a manner such that the totla charge distribution on each kernel remains the same. Thus you see there is a difference in the lattices of metals and ionic solids. Hence we  get the maleability of the Metals
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.
1052478
The charring you are referring to is called "Remelt"\n   It is seen in the EDM process as well.\nI am unfamiliar with the material you are referring to.\n   Can you offer more information?
1143581
Just answered this question for someone else:\n\nhttp://www.bestcrystals.com/ulexite.htm\n\nhttp://www.northwestnatureshop.com/department/Rocks_and_Minerals/Rock_and_Mineral_Specimens/592.html
732207
Pure crystals of garnet are used as gemstones. Garnet sand is a good abrasive, and a common replacement for silica sand in sand blasting. Mixed with very high pressure water, garnet is used to cut steel and other materials in water jets.
688922
Ferro-Chrome alloys, and a few other alloys.\n\nNickel Chrome, Cobalt Nickel Chrome Moly, Nickel Chrome, Irom Chrome Aluminim etc
798171
1) Rhyolites that cool too quickly to grow crystals form a natural glass or vitrophyre, also called obsidian\n\n2) amount of silica di-oxide, texture and color\n\n3) gold is found in quartz veins around igneous intrusion via hydrothermal fluid precipitation\n\n4) If we assume a slower but constant rate of cooling, then both minerals could feasibly form well shaped crystals at the same time (phaneritic texture) .  If we assume a slow than fast cooling, then possibly only plagioclase would form (porphyritic texture) due to its position in Bowen's reaction series.
218588
Aluminum as an ion has a 3+ charge, and oxygen as an ion has a 2- charge. So, to balance out these charges and get a neutral compound, the formula for aluminum oxide is Al2O3.\n\nAnd, no, aluminum oxide isn't just transparent aluminum. Definitely not. The crystal form of aluminum oxide is what's better known as rubies and sapphires.
445892
Salt crystals can, but Bultfonteinite is usually white. So that may be what you are looking for. I found a link for you with a pic so you can see if it is what you are refering to.\nThe website also has other crystals just in case that is not it, you should be able to find it there.
613277
A crystal (most likely from a Greek word which means "ice") is a solid in which the constituent atoms, molecules, or ions are packed in a regularly ordered, repeating pattern extending in all three spatial dimensions.\n\nGenerally, crystals form when they undergo a process of solidification. Under ideal conditions, the result may be a single crystal, where all of the atoms in the solid fit into the same crystal structure. However, generally, many crystals form simultaneously during solidification, leading to a polycrystalline solid. For example, most metals encountered in everyday life are polycrystals. Crystals are often symmetrically intergrown to form crystal twins.\n\n\nWhich crystal structure the fluid will form depends on the chemistry of the fluid, the conditions under which it is being solidified, and also on the ambient pressure. The process of forming a crystalline structure is often referred to as crystallization.\nSynthetic bismuth crystal\nEnlarge\nSynthetic bismuth crystal\n\nWhile the cooling process usually results in the generation of a crystalline material, under certain conditions, the fluid may be frozen in a noncrystalline state. In most cases, this involves cooling the fluid so rapidly that atoms cannot travel to their lattice sites before they lose mobility. A noncrystalline material, which has no long-range order, is called an amorphous, vitreous, or glassy material. It is also often referred to as an amorphous solid, although there are distinct differences between solids and glasses: most notably, the process of forming a glass does not release the latent heat of fusion. For this reason, many scientists consider glassy materials to be viscous liquids rather than solids, although this is a controversial topic; see the entry on glass for more details.\nInsulin crystals\nEnlarge\nInsulin crystals\n\nCrystalline structures occur in all classes of materials, with all types of chemical bonds. Almost all metal exists in a polycrystalline state; amorphous or single-crystal metals must be produced synthetically, often with great difficulty. Ionically bonded crystals can form upon solidification of salts, either from a molten fluid or when it condenses from a solution. Covalently bonded crystals are also very common, notable examples being diamond, silica, and graphite. Polymer materials generally will form crystalline regions, but the lengths of the molecules usually prevents complete crystallization. Weak Van der Waals forces can also play a role in a crystal structure; for example, this type of bonding loosely holds together the hexagonal-patterned sheets in graphite.\n\nMost crystalline materials have a variety of crystallographic defects. The types and structures of these defects can have a profound effect on the properties of the materials.\nGallium, a metal that easily forms large single crystals\nEnlarge\nGallium, a metal that easily forms large single crystals\nA large artificial monocrystal grown by Saint-Gobain for the megajoule laser of CEA.\nEnlarge\nA large artificial monocrystal grown by Saint-Gobain for the megajoule laser of CEA.\n\nWhile the term "crystal" has a precise meaning within materials science and solid-state physics, colloquially "crystal" refers to solid objects that exhibit well-defined and often pleasing geometric shapes. Various shapes of such crystals are found in nature. The shape of these crystals is dependent on the types of molecular bonds between the atoms to determine the structure, as well as on the conditions under which they formed. Snowflakes, diamonds, and common salt are common examples of crystals.\n\nSome crystalline materials may exhibit special electrical properties such as the ferroelectric effect or the piezoelectric effect.\n\nThe behaviour of light in crystals is described by crystal optics. In periodic dielectric structures a range of unique optical properties can be expected as described in photonic crystals.\n\nCrystallography
444717
It is not a combination of iron and tin, or anything else besides protons, electrons, and neutrons.\n\nThere's a naturally occurring ore called bauxite, which was discovered near Les Baux in the south of France, which is refined to produce aluminum.\n\nAt this link   \n\nhttp://volcano.und.edu/vwdocs/minerals/bauxite.html\n\nthere's a pie chart showing where it is mined today.  A lot of it comes from Australia, but that's not the only source.
914315
Andalusite is a polymorph with two other minerals; kyanite and sillimanite. A polymorph is a mineral that shares the same chemistry but a different crystal structure with another, or other, minerals. A unique variety of andalusite is called "chiastolite". It contains black or brown clay and/or carbonaceous material inclusioned in the crystal. These inclusions are arranged in regular symmetrical shapes. Usually they are in the form of a cross or X. \n\nPHYSICAL CHARACTERISTICS:\nColor is white, red, brown, orange and green. \nLuster is vitreous. \nTransparency crystals are transparent to translucent. \nCrystal System is Orthorhombic; 2/m2/m2/m \nCrystal Habits include prismatic crystals with a square cross section terminated by a pinacoid. also massive and granular. \nCleavage is good in two directions. \nFracture is splintery to subconchoidal. \nHardness is 7.5 \nSpecific Gravity is approximately 3.15+ (above average) \nStreak is white. \nAssociated Minerals are cordierite, biotite, feldspars, quartz, kyanite and sillimanite. \nOther Characteristics: dark inclusions produce cruciform shapes in the variety, chiastolite. Index of refraction is 1.632-1.638. \nNotable Occurrences include Andalusia, Spain; Austria; California, USA and China. \nBest Field Indicators are crystal habit, color, inclusions (if present) and hardness.
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.
455972
There are many crystal shapes.  The standard is an elongated six sided coming to a pyramid like point at the top.  Some, however, are double terminated (have points at both ends). Some (such as garnets) have six sides, but are flat on top and almost roundish looking.  Others, such a mica, are in flat layers.  Others still, can come in cubes (such as pyrite)  Some crystals have no particular shape at all (globular)(such as malachite).  So there is no one particular crystal shape.
1129625
Here are some potential sources:\n\nhttp://www.bestcrystals.com/ulexite.htm\n\nhttp://www.northwestnatureshop.com/department/Rocks_and_Minerals/Rock_and_Mineral_Specimens/592.html\n\nI'm sure you could find more if you googled it like I did.
506691
Sapphirine (one "r") is a rare mineral, a silicate of magnesium and aluminium.Collected by Gem enthusiasts and sometimes cut into sapphire colored gemstones.