The great challenge of geographic origin determination is to connect the properties and
features of individual gems to the geology of their deposits. Similar geologic environments …

Corundum-rich (up to 55 vol.%) felsic dykes formed with albite,±K-feldspar,±hercynite
and±biotite-siderophyllite cut the lower crustal rocks exposed in the Ivrea–Verbano Zone …

Blue sapphire of gem quality was recently discovered in spinel–chlorite–muscovite rock
within meta-ultramafites near the Ilmenogorsky alkaline complex in the Ilmen Mountains of …

Abstract In the Hamadan region, Sanandaj-Sirjan Zone (SaSiZ), W Iran, a pegmatite-aplite
vein occurs that contains up to 15 vol% sapphire. The Hamadan sapphire is black to blue …

Greece contains several gem corundum deposits set within diverse geological settings,
mostly within the Rhodope (Xanthi and Drama areas) and Attico-Cycladic (Naxos and Ikaria …

The geotectonic setting for plumasite-type corundum occurrences is understudied, even
though it is of importance for the understanding of trace-element patterns used for …

Corundum is rarely found in situ within alkali syenites. A corundum-bearing syenite was
found in the Yushishan rare metal deposits of the eastern section of the Altyn Tagh fault in …

Kyshtymites are the unique corundum-blue sapphire-bearing variety of anorthosites of
debatable geological origin found in the Ilmenogorsky-Vishnevogorsky complex (IVC) in the …

Metamorphic gem corundum (mainly ruby) deposits are robust indicators of continent-
continent collision processes. However, a systematic link of primary magmatic blue sapphire …

Primary rubies in the Ailao Shan of Yunnan Province, China, are found in three layers of
marble. However, the origin and source rocks of placer rubies in the Yuanjiang area remains …