Thank you for submitting your item for appraisal. This appears to be a modern photograph / computer printed of the ambrotype photo sold at auction. All the defects visible in the original, including the colourful oxidation is reproduced. This means it is a photographic copy of the recently sold ambrotype sold at auction put on an old tintype to deceive you. Have a look at the edge, there should be a photograph on paper laid down on the tin. As such it would be a forgery of only decorative value.