The mineral alumina (Al2O3), as found native in a crystalline state. Transparent varieties are used as gemstones, including sapphire, which is the fine blue variety; the oriental ruby, or red sapphire; the oriental amethyst, or purple sapphire; and adamantine spar, the hair-brown variety. It is the hardest substance found native, next to the diamond.
A hard mineral that exists in the form of colored crystals, such as rubies and sapphires.
A gem species that is found in many colors. Red corundum is called ruby and all other varieties are called sapphire. Blue Sapphire is best known, however pink, green, and yellow sapphire are also relatively popular.
It is a crystallized aluminum and oxygen gem mineral. The most valuable type of corundum are ruby and sapphire.
Corundum (aluminum oxide Al2O3) is the hardest mineral other than diamond, though only 1/140 as hard. Red corundum is ruby, other colors are called sapphires. There is no clear demarcation of color to define which gems are called rubies or sapphires. Light red, pink or violet corundums are usually classified as sapphires with the name ruby reserved for truly red stones. The coloring in ruby comes from chrome, pigment in blue sapphire is iron and titanium, and in violet stones, vanadium. Iron content causes yellow and green tones.
Native alumna, or aluminum oxide, Al2O3, occurring as rhombohedral crystals and also in masses and variously colored grains. Applied specifically to nontransparent kinds used as abrasives. It is hardest mineral except the diamond. Corundum and its artificial counterparts are abrasives especially suited to the grinding of metals.
a hard form of alumina; used as the grit for sandpaper.
very hard mineral used as an abrasive
a mineral that sapphires and rubies come from
an extremely hard mineral from which gem varieties such as ruby and sapphire fall under. Corundum contains aluminum oxide, iron, magnesia or silica.
A gem mineral. Ruby and sapphire are from the corundum family.
Group of minerals that includes Rubies and Sapphires.
The mineral species which includes rubies and sapphires.
The mineral form of alumina. It includes the precious gemstones ruby, sapphire and yellow sapphire.
Chiefly aluminum oxide. Spirit of wine Ethanol (ethyl alcohol).
Corundum is called ruby or sapphire, depending on the color. In its rare pure form, corundum is colorless and called white sapphire. Corundum has a hardness of 9.
A natural mineral whose principle composition is aluminum oxide. Historically a mineral mined in the Middle East and India for use in grinding wheels, Corundum has been replaced by synthetic abrasive minerals, which offer more uniform and consistent physical properties.
(1728) The second hardest of all minerals, corundum consists of aluminium oxide and occurs in massive form and as variously coloured crystals, which include the ruby and sapphire. Apart from red and blue, the colour range includes orange, yellow, grey-to-brown, black and bronze with pearly lustre, pink, green and purple.
The mineral composition that makes up the ruby and sapphire family of gemstones.
Corundum is a gem mineral composed of gas oxygen and light metal aluminum. The two most valuable corundum include Ruby and Sapphire. Due to its hardness, brilliance and variety, some experts consider corundum to be the most important and most versatile of the gem families.
Corundum is an aluminum oxide, which is called a ruby when red and sapphire in other colors (including lighter shades of red). The different colors are caused by the presence of chrome, iron, titanium, etc.
That extremely hard mineral from which emery is made.
Corundum manifests itself in two forms of stone - Rubies and Sapphires. Part of the same family, the color of these stones depends on the oxides present in their composition. With a hardness of 9, it is one of the hardest minerals, second only to diamonds.
A gem mineral of crystallized aluminum and oxygen. Ruby and sapphire are the most valuable corundum.
A gem mineral of crystallised aluminium and oxygen. Ruby and sapphire are the most valuable corundum
Corundum is a crystalline form of aluminum oxide and one of the rock-forming minerals. It is naturally clear, but can have different colors when impurities are present. Transparent specimens are used as gems, called ruby if red, while all other colors are called sapphire.