Tintype dating

I am resending this with just one tintype, as it seems the ealier attempts with two (resized) tintypes did not go through.

In my deceased mother's belongings was a 19th century photo album, leather bound, two clasps, single CDV per page (room for 50 photos).  There is no index.  After some effort I've determined that it was created 1863/64 (for example, no tax stamps).  There are 32 CdVs, nine mounted tintypes (either Gems or sixteenth-plate) and one  unmounted sixth plate (2 5/16" by 3 3/4") with left corners cut.  The first fifteen pages are either blank or with photos taken and added  later, photos taken contemporaneously and added later, or photos rearranged later.  The sixth-plate tintype is in this section, at page 9.  
The album was created in Herkimer County New York by either Phebe Cummings Nichols (1807-1889), second wife of Horace Nichols, or her spinster sister, Esther Cummings (1803-1887; I lean slightly towards Esther), and is focused on the children of Horace and his first wife, with some photos of their sister, Margaret Cummings Wheelock (1809-1886) and her family.  Margaret Cummings Wheelock is my great great grandmother.  I think two of the CdVs are of her, one is her husband, Danford Wheelock (1802-1866), and several (in the rearranged section) of their children and grandchildren.
After Horace's death, Esther moved in with Phebe; after Esther's death, Phebe moved in with her niece, the widowed Nancy Wheelock Avery (1837-1925), Margaret's daughter and my great grandfather's elder sister.  Nancy wound up with the album and did some of the rearranging (probably) and adding (certainly).  After her death and, probably, the death of one or both of her two children (who never married), the album wound up with my grandmother,  Charles Wheelock's daughter.  She may have also have done some rearranging/adding.  This is all guesswork, but I have my reasons which I would be happy to share.
I think the sixth-plate tintype may be a photo of my great grandfather, Charles Wheelock (1849-1928), but dating is obviously everything.   I have enclosed two copies.  One is a scan, getting the color as close as I can (brownish).  The other is enhanced, showing some more detail.
I would be grateful for any opinions on when this was taken.