Kyanite on Ruby

Blue and red form a striking complementary contrast, yet specimens combining both vivid hues are exceptionally rare. This rarity stems from the fact that the same chromophoric trace-element are actually difficult to make minerals apparent distinct colors, although possible. For such color combo, you need muti-stage crystallization that changes fluid composition, such as a ruby core rimmed by sapphire; or simply crystallize two minerals that takes different elements and associated together, such as blue fluorite associate with rhodochrosite; or, you got lucky.

Since 2007, an increasing volume of high-quality rubies from Winza, Tanzania has entered the gem market, rapidly establishing the area as a world-class ruby locality. These gem-quality corundums occur in Paleoproterozoic Usagaran Belt amphibolitic dikes, which host most of the region’s ruby deposits. Amphibolite originating from the metamorphism of gabbroic and dunitic rocks is an important source of ruby. You can only find ruby in such high pressure, mafic rocks to meet the stability field and enough Cr to make it red. At high pressure, kyanite will also form, which is the blue mineral herein. If Ti and Fe content is high, you will have sapphires and kyanites will be ink-blue. Significant amount of Cr and V (plus some Fe and Ti) will make kyanites greenish blue, a more attractive color. So many interesting projects in different geology fields can be generate when study high pressure these metamorphic rocks, this just something basic and in brief.

The ruby features an intense red color, partial gemmy; plus the kyanite make an overall 鸡你太美-shape (a famous, funny looking).

Ruby and Kyanite, 3.1cm, Winza, Mpwapwa District, Dodoma Region, Tanzania

Jingnan (Tom) Zhang Coll & Photo