Origin of Blue Sapphire in Newly Discovered Spinel–Chlorite–Muscovite Rocks within Meta-Ultramafites of Ilmen Mountains, South Urals of Russia: Evidence from Mineralogy, Geochemistry, Rb-Sr and Sm-Nd Isotopic Data

Blue sapphire of gem quality was recently discovered in spinel&ndash

Mineralogical-geochemical features of corundum Miaskite-pegmatite from mine no. 210 (Ilmeny mountains, South Urals): preliminary results

Miaskite-pegmatite of mine no. 210 exhibits an unusual mineral composition for the Ilmeny Mountains. It contains a signifcant amount of sapphire-like corundum (uncommon of nepheline-bearing pegmatites) and various Th-bearing minerals («thoro-aeschinite», pyrochlore, phosphates). Pegmatite has a zonal structure, in which the central nepheline and lateral feldspar zones difer in composition of rock-forming and accessory minerals. Corundum is found in all zones of pegmatite. Accessory minerals of the central, eastern, and western zones include (i) Ti-niobates (columbite, pyrochlore, srilankite), zircon, spinel and thorianite, (ii) columbite, pyrochlore and zircon, and (iii) columbite, «ilmenor…

Rubies and Sapphires from Snezhnoe, Tajikistan

Sapphire-bearing magmatic rocks trace the boundary between paleo-continents: A case study of Ilmenogorsky alkaline complex, Uralian collision zone of Russia

Abstract Metamorphic gem corundum (mainly ruby) deposits are robust indicators of continent-continent collision processes. However, a systematic link of primary magmatic blue sapphire occurrences to orogenic belts is less understood. An example is the Ilmenogorsky alkaline complex, within the Ilmen Mountains region and part of the Uralian orogenic belt. The mobile belt is a product of the collision among Kazakhstania, Laurussia, and Siberia continents prior to the closure of the Paleo-Uralian ocean and formation of the Laurasia supercontinent (330–250 Ma). It is believed that the alkaline complex became inсluded into the separate Sysertsk-Ilmenogorsk microcontinent with unconstrained border…

Corundum Anorthosites-Kyshtymites from the South Urals, Russia: A Combined Mineralogical, Geochemical, and U-Pb Zircon Geochronological Study

Kyshtymites are the unique corundum-blue sapphire-bearing variety of anorthosites of debatable geological origin found in the Ilmenogorsky-Vishnevogorsky complex (IVC) in the South Urals, Russia. Their mineral association includes corundum-sapphire, plagioclase (An61&ndash

Morphological and chemical evolution of corundum (ruby and sapphire): Crystal ontogeny reconstructed by EMPA, LA-ICP-MS, and Cr3+Raman mapping

The term “ ontogeny ,” which is commonly used in biology, was introduced into the Earth sciences in 1961 to include the genesis and evolution of single crystals and crystal aggregates. The term encompasses nucleation , growth , alteration , and destruction . We present results of studies concerning the ontogeny of natural corundum (rubies and sapphires), and the chemical and morphological evolution of corundum crystals from deposits in Africa (Kenya, Tanzania, Madagascar) and Southeast Asia (Vietnam). Trace-element compositions indicative for different corundum habits were determined by rim-to-rim LA-ICP-MS and electron microprobe analyses. Raman spectroscopy was applied for Cr 3+ photolumi…