Green oil lamp

This was my grandmother's. It was always on her table. She would lite it and sit at the table and say her prayers and do her rosary. When I got it I would like it during rainstorms and sit with my kids at the table and tell stories. I didn't like having the TV on or anything electrical on. I don't know the age of this lamp. If anyone is familiar with it please let me know what era this is from.