Jamesonite is a sulfosalt mineral, a lead, iron, antimony sulfide with formula Pb4FeSb6S14. With the addition of manganese it forms a series with benavidesite. It is a dark grey metallic mineral which forms acicular prismatic monoclinic crystals. It is soft with a Mohs hardness of 2.5 and has a specific gravity of 5.5 - 5.6. It is one of the few sulfide minerals to form fibrous or needle like crystals. It can also form large prismatic crystals similar to stibnite with which it can be associated. It is usually found in low to moderate temperature hydrothermal deposits.
Neptis jamesoni, or Jameson's large sailer, is a butterfly in the family Nymphalidae. It is found in Nigeria (the Cross River loop), Cameroon, the Republic of the Congo, the Central African Republic and the Democratic Republic of the Congo.
Calleagris jamesoni, Jameson's flat or Jameson's skipper, is a butterfly in the family Hesperiidae. It is found in Angola, the Democratic Republic of the Congo, Tanzania, Zambia, Malawi, Mozambique, Zimbabwe and Botswana. The habitat consists of Brachystegia woodland, savanna and forest margins.