What is corundum luster?
Colorless (harder than the streak plate) Luster. Adamantine to vitreous.
What is mineral corundum?
corundum, naturally occurring aluminum oxide mineral (Al2O3) that is, after diamond, the hardest known natural substance. Its finer varieties are the gemstones sapphire and ruby (qq. v.), and its mixtures with iron oxides and other minerals are called emery (q.v.).
What gemstones are corundum?
The corundum family of gemstones consists of ruby and sapphire. Corundum is very compact, dense, and lacks gemstone cleavage. It’s also the second hardest natural mineral after diamond.
How can you tell if a rock is corundum?
Pure corundum is colourless and clear if transparent or pale white if opaque. This mineral also has low dispersion so the value of the stones comes not from fire generated (as in diamond), but rather from the intensity of colours seen.
What is the use of apatite?
The primary use of apatite is as a source of phosphate in the manufacture of fertilizer and in other industrial uses. It is occasionally used as a gemstone.
What is synthetic corundum?
Synthetic corundum is produced from pure alpha aluminum oxide free from potash (corresponds to white sapphire, which is known as walderite) in an oxyhydrogen flame.
Why is corundum a mineral?
Corundum is a crystalline form of aluminum oxide (Al2O3) with traces of iron, titanium and chromium. It is a rock-forming mineral. It is one of the naturally transparent materials, but can have different colors when impurities are present. Transparent specimens are used as gems such as sapphires and rubies.
How corundum is formed?
Corundum is a high-temperature mineral that forms naturally by metamorphism of alumina-rich rocks under amphibolite and granulite facies conditions, and at temperatures between 500° and 800°C (Simonet et al., 2008).
Is corundum a precious gem?
Corundum is a mineral species that includes two world’s most precious gemstones, ruby and sapphire. Since they are the same mineral, sapphire and ruby are often found together. Sapphire is far more common variety, as ruby requires a specific element and an appropriate host rock to supply its essential chromium.
Is Garnet a corundum?
When someone lists the most famous gemstones such as diamond, topaz, aquamarine, emerald and garnet, corundum does not usually get mentioned. However, its two varieties are sure to be on any list of gemstones. The red variety of corundum is known as ruby and all the other colors of corundum are known as sapphire.