Hi there /r/AskHistorians! I am wondering if anyone here knows anything more about the avocado pit ink that was used by Conquistadors? Apparently there are surviving documents that used this ink, however I am hard pressed to find any examples online of this historical ink. It is supposed to be red in color, indelible, and more well behaved than other historical inks (such as iron gall). Any information or examples of this would be greatly appreciated, but it is just for my curiosity as I really like ink.
To clarify: I was wondering if anyone could point me towards some historical documents/examples somewhere online where this ink was used and can be viewed. I know there is a tutorial on how to make it, but I was really looking for more of a historical document or use.
You might want to consider looking for sources in Spanish. It'd be "tinta de aguacate en la colonia" or "tinta de aguacate españoles/conquistadores".
Here is once instance, written by Eduardo Galeano, who is an acclaimed historian and journalist. Last paragraph.