=treasure diver ]
Maybe a Ferrotype or a calotype or a Dauguerreotype. Looks like from Fox Talbots time around 1830 to 1839. Since it looks like a negative tintype is my guess.
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A) Correct diver, they polished the copper plate to use as a mirror to view the positive which was composed of gelatine wth light sensative silver suspended in it.
I experimented with this when learning Photography, black and white picture days.
Till Eulenspiegle de La Mancha