Yes, the entire index as a source for a bibliography. A specific card as an entry (similar to a page in a book). Here's an example as a bibliographic entry, CMOS format.
Indiana State Library. "Indiana Bible Records Index." Card file. No date, last updated in 1970s. Indiana State Library Genealogy Division, Indianapolis.
The card file is not published, so the title is in quotes rather than italicized. If I do it as a book, then it will be italicized by Zotero.
I can enter Repository and Repository Location, but they don't appear in the bibliography entry. I am using an iPad right now. Not sure it would work better with a PC or Mac.
Manuscript works well as long as I put the repository in the Archive field along with the location of the library, e.g. Indiana State Library, Indianapolis. If I put Indianapolis in the Place field, the place gets inserted before the date. Manuscript is acceptable, though. I realize that Zotero cannot create an item type for every possible item and every possible citation style.
Indiana State Library. "Indiana Bible Records Index." Card file. No date, last updated in 1970s. Indiana State Library Genealogy Division, Indianapolis.
The card file is not published, so the title is in quotes rather than italicized. If I do it as a book, then it will be italicized by Zotero.