I was able to find three different allotropic forms of sulfur. The first is called orthorhombic. This allotrope forms when sulfur vapors cool. This is the most stable form of sulfur. The second allotrope of sulfur is monoclinic. Monoclinic sulfur forms when liquid sulfur cools quickly in air. "Monoclinic sulfur exists between the temperatures of 96°C and 119°C and reverts back to the orthorhombic form when cooled." The third allotrope of sulfur is amorphous sulfur. Amorphous sulfur is the result of a very rapid cooling of very hot sulfur. "Amorphous sulfur is soft and elastic and eventually reverts back to the orthorhombic form."