when you click on some resouces it says found colony and some don't. iron , gold , stone , horses and diamonds do and cotton, silk , rice, hemp, spices don't . I haven't cheked all yet. and there are some special recourses sticked together no distance between each other . I think it's a bug.
Well, it's hardly to say it's a bug because colonization stage is still far away, so functionality is not harmed by any means.