Avicennite (thallium(III) oxide) is an oxide mineral. It is an isometric-diploidal grayish black mineral containing oxygen and thallium. It is not radioactive. It was discovered around the Dzhuzumli village, Samarqand, Uzbekistan. It is named after Avicenna, a Persian doctor, and polymath.

General Information

  • Category: Mineral
  • Formula: Tl2O3
  • Crystal system: Cubic
  • Crystal class: Diploidal (m3)
  • Hardness: 1½ – 2½ on Mohs scale.


  • Color: Grayish black with brownish black tint
  • Mohs scale hardness: 1,5 to 2,5
  • Lustre: Metallic
  • Transparency: Opaque
  • Streak: Greyish black, black with a brownish tint
  • Tenacity: Very brittle
  • Fracture: Irregular/Uneven, Hackly, Conchoidal
  • Density: 8.9 g/cm3 (Measured) and 34 g/cm3 (Calculated)


In the weathered zone of a hematite-calcite vein cutting banded marmorized and silicified limestones near a granite-gneiss contact (near Dzhuzumli, Tajikistan); formed by oxidation of carlinite in carbonaceous gold ores in silicified limestones and quartz (Carlin mine, Nevada, USA).

Name: For the medieval Uzbek (Persian) scholar and physician, Abu ‘Alı al-Husayn ibn ‘Abd Allah ibn Sına (Avicenna) (930–1037), who lived in Bukhara, Tajikistan.


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