Corundums Research Articles

Introducing Semi-gem quality blue corundum from the Alvand complex, Hamedan, west Iran

Semi-gem quality corundum crystals are formed in a syenite pegmatite dyke in the Alvand igneous-metamorphic complex in west Iran. The dyke is intruded the igneous rocks and the surrounding hornfelses. Corundum is mainly associated with K-feldspar in the rocks and makes crystals 2 to 60 mm across. It shows gray, bluish-gray, pale blue, ink blue and dark blue colours. The crystals show colour zoning and trapiche-like zoning in hand specimens and under the microscope. The main mineral phase inclusions in corundum crystals are muscovite, phlogopite, hercynite and Nb-Ta oxides. LA-ICP-MS and electron microprobe analyzes indicate wide range of Fe/Mg, Fe/Ti, Ti/Mg and Ga/Mg ratios for the analyzed crystals while variation of Cr/Ga ratio is limited. The high Fe and Ga and low Mg and Cr contents suggest a magmatic origin for these corundums. Ti content was found as the main factor controlling the colour.

On corundums from Umba Valley, Tanzania

On corundums from Umba Valley, Tanzania

Gemmological Properties of Synthetic Corundums Coated by Lechleitner

Gemmological Properties of Synthetic Corundums Coated by Lechleitner

Contribution Towards the Identification of Treated Corundums: Heat and Diffusion Treated Rubies

Contribution Towards the Identification of Treated Corundums: Heat and Diffusion Treated Rubies