Streak is a mineralogical term to describe the colour produced by rubbing a piece of mineral against a (porcelain) neutral background.
Since Opal is made from silica spheres, I'd expect a white streak, but meaningless. There may be powdered spheres left behind from the opal structure.
Corundum has a streak that is typically colorless, making it difficult to determine on a streak plate. The hardness of corundum (9 on the Mohs scale) can also affect the accuracy of the streak test, as it can scratch the streak plate instead of leaving a distinct streak.
Two minerals that do not leave a streak on a streak plate are quartz and fluorite. Both minerals have a hardness higher than that of the streak plate, so they will not leave a streak when rubbed against it.
THE EIGHT WAYS TO I.D. A MINERALThe eight ways to identify a mineral such as corundum are 1 hardness 2 crystal shape 3 special features 4 density 5 streak 6 luster 7 cleavage or fracture 8 color. (to find out hardness look up "Mohs scale of hardness" everything else you could search it on google or bing)
Small traces of iron are responsible for much of the color found in corundum (saphire) gems. Ruby, however, does not contain iron and will not be affected by a magnet. To be technical however, I should point out that corundum is not magnetic. Corundum will not attract other pieces of iron to itself (as far as I know). To simply answer that corundum is not magnetic would have been misleading.
Corundum, also known as aluminum oxide, is not magnetic. It is a diamagnetic material, meaning it does not have any magnetic properties and is very weakly repelled by magnetic fields.
Corundum has no streak color. Because of being a clear white or light blue, its streak is actually clear.
Corundum has a streak that is typically colorless, making it difficult to determine on a streak plate. The hardness of corundum (9 on the Mohs scale) can also affect the accuracy of the streak test, as it can scratch the streak plate instead of leaving a distinct streak.
Corundum has no streak color. Because of being a clear white or light blue, its streak is actually clear.
Topaz (8), corundum (9), and diamond (10).
Two minerals that do not leave a streak on a streak plate are quartz and fluorite. Both minerals have a hardness higher than that of the streak plate, so they will not leave a streak when rubbed against it.
No it does not work with all minerals. For if you did not know streak plates have a hardness of 7 (maybe a little lower or higher) on the Mohs scale. Some minerals are harder than 7 though. If they are harder they will not work with the streak test. some examples are Diamond, topaz, and corundum.
Corundum.
Corundum ( (Al_2O_3) ) is hexagonal in crystal structure.
Corundum is in the trigonal crystal system.
Corundum is used for jewlery
THE EIGHT WAYS TO I.D. A MINERALThe eight ways to identify a mineral such as corundum are 1 hardness 2 crystal shape 3 special features 4 density 5 streak 6 luster 7 cleavage or fracture 8 color. (to find out hardness look up "Mohs scale of hardness" everything else you could search it on google or bing)
Red corundum is called ruby.