I'd say this used a pin fire cartridge. The pin fire is recognized by it's metallic cartridge with a pin sticking out of it as the primer. The hammer strikes the pin and the pin ignites the powder charge in the cartridge. You can see the little notch on each of the barrel recesses on the upper side of the double barrel.
I'd put its date between about 1860 and 1880. I'm afraid I'm not an expert in this, although it's a cute pocket pistol.