corundum, Mozambique.12, gems

Rubies have recently been discovered in northern Mozambique, specifically in Niassa Province (M’sawize village, Lichinga district) and Cabo Delgado Province (Montepuez area). These rubies display internal features such as twin planes, fluid-film inclusions, negative crystals, and crystalline inclusions. Many of the crystalline inclusions are colorless to green amphibole (possibly pargasite), along with confirmed apatite and fine needles producing “silk.” Some fractures contain material resembling hematite. Infrared spectra of unheated Mozambique rubies show a broad absorption band at 3309 and 3081 cm⁻¹, which disappears after heating; weak bands at 2074 and 1980 cm⁻¹, likely from diaspore, may also be present. EDXRF analysis reveals Cr contents of 0.3–0.8 wt.% and Fe contents of 0.2–0.5 wt.%, higher than typical non-basalt-related rubies but lower than basaltic rubies. Most Mozambique rubies have been heat-treated, often leaving flux residues in fissures.