Wrought iron is an iron alloy with a very low carbon content which has fibrous inclusions known as slag.  This is what gives it a "grain" resembling wood. 

Wrought iron was once the most common form of malluable iron.  It reached it's peak use in the 1860's but declined with the use of mild steel. 

Wrought iron is no longer produced on a commercial scale.  Many products today, including wrought iron fireplace screens, are made of mild steel but called wrought iron because they were once made of or resemble it. 

True wrought iron is used for historic structures.  You can still admire the classic look of wrought iron with your wrought iron fireplace screen.