Agreed, the clothes, hat, hair, furniture and even the pose are all perfect examples of full fledged 1870s sytle, meaning probably toward the middle or end of the decade when the clear separation from 1860s fashion had occurred.
The woman is considered an adult which would put her anywhere after about 18. I would guess she is probably in her younger twenties.
Also, (people will think I'm a quack for saying this all the time), but I would bet money that this is a later reprint of an original photo because A) it's on photo paper without a visible mount and B) there appears to be some light retouching around the eyes and on the face in general. Probably a turn of the century reprint as paper photos without mounts didn't become very popular until after about 1900.
