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The Black Prince's Ruby is a large, irregular cabochon red spinel weighing 170 carats (34 g) set in the cross pattée above the Cullinan II diamond at the front of the Imperial State Crown of the United Kingdom. [1] The spinel is one of the oldest gems in the Crown Jewels of the United Kingdom, with a
Calcite. Manganoan calcite (var.); Caledonite; Canasite; Cancrinite. Vishnevite; Carletonite; Carnallite; Cassiterite; Catapleiite; Cavansite; Celestite; Ceruleite ...
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]
Inverse spinel structures have a different cation distribution in that all of the A cations and half of the B cations occupy octahedral sites, while the other half of the B cations occupy tetrahedral sites. An example of an inverse spinel is Fe 3 O 4, if the Fe 2+ (A 2+) ions are d 6 high-spin and the Fe 3+ (B 3+) ions are d 5 high-spin.
Amethyst crystals – a purple quartz Apophyllite crystals sitting right beside a cluster of peachy bowtie stilbite Aquamarine variety of beryl with tourmaline on orthoclase Arsenopyrite from Hidalgo del Parral, Chihuahua, Mexico Aurichalcite needles spraying out within a protected pocket lined by bladed calcite crystals Austinite from the Ojuela Mine, Mapimí, Durango, Mexico Ametrine ...
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.
After color follows clarity: similarly to diamonds, a clear stone will command a premium, but a ruby without any needle-like rutile inclusions may indicate that the stone has been treated. Ruby is the traditional birthstone for July and is usually pinker than garnet , although some rhodolite garnets have a similar pinkish hue to most rubies.
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 ...