White Europeans are used as symbols of self-deception, and objects with an alabaster quality are symbols of barriers to inner truth. This event and the doctrine of colonialism bought into at his time obviously influenced his views at the time of Heart of Darkness publication The Europeans are far more interested in ivory that in civilizing the Natives.
Conrad was merely presenting Congo as he saw it, through Marlow. Over the course of Heart of Darkness, certain aspects of colonialism and those involved are revealed in a darker form than usual.
In Europe, colonialism was emphasized as being a Congo has been described as wild and violent, and it becomes the embodiment of the untamed country and its natives that need to be civilised. Conrad begins with a focus on what the Company overtly tells the public: They are going into the Congo to civilize the Natives.
It is very clear, without any debate that the novel comes across as very racist and offensive to not just the natives of Congo, but to all that belong to Africa.
The white men being superior to everyone are required to educate and civilise the rest of the world. The main purpose and the results have stayed the same. To the Europeans it is imperative that they attain wealth, power and prestige. Conrad lived through a time when European colonies were scattered all over the world.
Most of the story takes place in the Congo which is now known as the Republic of the Congo.