Tintypes, not tin but iron, the rouge on the cheek was a tint placed by the photographer before applying the enamel or lacquer coating. Customers could have their picture taken and walk away with it in just a few minutes making them popular at carnivals and fairs. Helping to keep them in demand from the 1860's until the 1900's was the fact they were also sturdy and cheap.
From the little I've read about dating women's clothing I'm guessing this was the late 1880's-1890's. The straight skirt, length, narrow shoulder were some of the characteristics I tried to date.