Wiktionary
avicennite
n. (context mineral English) An isometric-diploidal grayish black mineral containing oxygen and thallium.
Wikipedia
Avicennite
Avicennite ( Thallium(III) oxide) is an oxide mineral. It was discovered around the Dzhuzumli village, Samarqand, Uzbekistan. It is named after Avicenna, a Persian doctor and polymath.