Baghdadite

baghdadite

zirconium

foshagite

baddeleyite

Images
Formula: Ca6Zr2(Si2O7)2O4
Sorosilicate (Si2O7 groups), wöhlerite group, zirconium-bearing mineral
Specific gravity: 3.48
Hardness: 6
Streak: White
Colour: Colourless, pale brown, beige, pale yellowish
Solubility: Slowly soluble in concentrated hydrochloric acid, insoluble in concentrated nitric and sulphuric acids (Dana)
Common impurities: Al,Fe,Mg,Na
Environments

Metamorphic environments

Baghdadite is extremely rare. It occurs in melilite skarn in contact with banded diorite, in roof pendant xenoliths of calc-silicate marble and hornfels (Webmin). In melilite skarn Baghdadite is associated with åkermanite, perovskite, schorlomite, monticellite, wollastonite, foshagite, calcite, phlogopite, spinel, cuspidine, baddeleyite, pyrrhotite, djerfisherite and valleriite (HOM).
In banded diorite it is associated with albite variety andesine, kaersutite, titanian augite, ilmenite, titaniferous magnetite and xonotlite (HOM).

Localities

At the type locality, the Dupezeh mountain, Hero, Qala-Diz, Sulaymaniyah, Iraqi Kurdistan, Iraq, baghdadite has been found in melilite skarn in contact with banded diorite, composed chiefly of albite variety andesine and kaersutite with ubiquitous titanium-rich augite, ilmenite and titaniferous magnetite. The melilite skarn is cut by randomly distributed veinlets of foshagite and a few small patches of monticellite and wollastonite surrounded by a xonotlite rim. The mineral assemblage of the melilite skarn was composed of melilite, perovskite, garnets (grossular, schorlomite and Zr-schorlomite), and in addition monticellite, wollastonite, titanium-rich augite and foshagite with accessory phlogopite, chlorospinel, cuspidine, baddeleyite, baghdadite, pyrrhotite, djerfisherite, and valleriite. The grade of metamorphism lies within the pyroxene hornfels facies (MM 50.119-123).

Formation

Baghdadite is a product of high-temperature skarn formation and is considered to form by a reaction involving the pre-existing wollastonite and calcite in the country rock and zirconium evolved from the intrusive igneous liquid.
4CaSi03 + 2CaC03+ 2Zr02 → Ca6Zr2(Si207)2O4 + 2C02
(MM 50.119-123)

Back to Minerals