Manganocalcite

I had volunteer duty at the library tonight.  It's a short stint - 5 p.m. to 7 p.m.  I try to get there well ahead of time so the librarian can let me know if there are missing books to look for, new policies, or just to let her leave a little early.  The librarian was gone at 5 when two teenage brothers walked in.  These guys had come in last week and one had spent an inordinately long time in the bathroom while the other read a book.  Tonight right away that one walked through the doors into the other part of the building where the bathrooms are.  Forty minutes later he came back and immediately his brother went into the bathroom.  He stayed there until their mother came to pick them up before closing.  Last week I had wondered if one of the brothers might be helping out the cleaners that are working in that area but the cleaner was gone today.  None of my other ideas of what takes them so long were as palatable.  I'll talk to the librarian and see if  bathroom monitor is also part of my duties.