check out our:
"But both the diabolic love and the unearthly hate of the mysteries it had penetrated fought for the possession of that soul satiated with primitive emotions, avid of lying fame, of sham distinction, of all the appearances of success and power." (3.37)
Kurtz may have gone over to the dark side, but he's not exactly going quietly. He's torn between loving and hating Africa and the colonial project—which actually seems like a logical response for someone in his position.
"His [Kurtz's] was an impenetrable darkness. I looked at him as you peer down at a man who is lying at the bottom of a precipice where the sun never shines." (3.40)
Kurtz is so evil now that light can't even touch him. Metaphorically.
"I was fascinated. It was as though a veil had been rent. I saw on that ivory face the expression of sombre pride, of ruthless power, of craven terror - of an intense and hopeless despair. Did he live his life again in every detail of desire, temptation, and surrender during that supreme moment of complete knowledge?" (3.42)
As Kurtz dies, Marlow sees a parade of negative emotions pass over his face—pride, ruthlessness, terror, and despair. Contrast that with the white, calm connotations of "ivory," and you'll see why this book has us scratching our heads so thoughtfully.