Old examples of this famous replacement of stibnite by the rare mineral stibiconite, are well known from old books and exhibits of Mexican treasures. They mostly seem to have come out prior to the mid 1970s, and so it is likely that this entered the Avila collection as one of the earliest of finds he brought out to market himself, or obtained from an older collection down there. This is a particularly choice, aesthetic example, showing complete replacement of the original stibnite by the later mineral. When we grew up, I was taught that this was probably a process that happened in geological time within the deposit, but the new science seems to indicate that many such replacements happened quickly, even as the original mineral formed or very shortly thereafter, and then waited for discovery all those eons since. This is a classic of Mexican collecting, in good display size.