Search results
Results from the WOW.Com Content Network
Sapphirine is a rare mineral, a silicate of magnesium and aluminium, with the chemical formula (Mg,Al) 8 (Al,Si) 6 O 20 (with iron as a major impurity). Named for its sapphire-like colour, sapphirine is primarily of interest to researchers and collectors: well-formed crystals are treasured and occasionally cut into gemstones.
Polyhedral representation of spinel MgAl 2 O 4. Spinel (/ s p ɪ ˈ n ɛ l, ˈ s p ɪ n əl / [7]) is the magnesium/aluminium member of the larger spinel group of minerals. It has the formula MgAl 2 O 4 in the cubic crystal system. Its name comes from the Latin word spinella, a diminutive form of spine, in reference to its pointed crystals. [5]
The mineral ceylonite has the chemical composition of (Mg, Fe 2+) Al 2 O 4, putting it into a group of minerals known as the spinel group, or the oxide spinels. The oxide spinels have a formula of the model [A][B] 2 O 4; where [A] is commonly Fe 2+, Mg 2+, or Mn 2+, and [B] is Fe 3+, Al 3+, or Cr 3+. It is an iron-rich variety of the spinel ...
The mineral spinel MgAl 2 O 4 has a normal spinel structure. In a normal spinel structure, the ions are in the following positions, where i, j, and k are arbitrary integers and δ, ε, and ζ are small real numbers (note that the unit cell can be chosen differently, giving different coordinates): [16]
Along with its sister publication, the older Handbook of United States Coins (The Official Blue Book), it is considered an authoritative U.S. coin price guide. The Guide Book and Handbook got their nicknames (and now official trademarks), the "Red Book" and the "Blue Book," due to their respective solid red and blue covers. [1]
Before you buy a new RV or sell one, read our article on RV values, RV trade-in values, RV Blue Book and more. ... A Comprehensive Guide to RV Values and Trade-ins. June 3, 2021 at 1:35 PM.
In 1838, in the inventory of crown items, the stone under the cross was called a “large ruby”, and in the inventory of 1865 it was already listed as “an irregularly shaped spinel ruby, worth 100,000 rubles”. [15] Since 1967, the crown, and along with it the historical spinel, has been an exhibit of the Diamond Fund.
Kizik makes some of the best shoes our editors have tested for those who have arthritic feet.The Kizik Athens are easy to slide into and have the love of more than 2,500 reviewers. And during ...