What is "ahlfeldite"

n. (context mineral English) A secondary selenite mineral found in Bolivia.

Ahlfeldite (( Ni, Co)[ Se O]·2 HO) is a mineral of secondary origin. It's named after Friedrich Ahlfeld (1892–1982), a German-Bolivian mining engineer and geologist. Its type locality is Virgen de Surumi mine, Pakajake Canyon, Chayanta Province, Potosí Department, Bolivia.