This substance can either be a light brown, powdery solid, or it can be a green crystalline solid. The first state is when this substance is in its anhydrous form, and it’s called tolbachite. As copper chloride absorbs moisture from the air, it becomes crystalline, and then it’s called eriochalcite. Both of these substances are stable but highly toxic. Copper chloride is found in a variety of applications, including the manufacture of several different chemicals, including chlorine. It is corrosive to aluminum, so it can be used as an etching agent for aluminum surfaces. Copper chloride can also be found in a variety of dyes, fungicides, and printing chemicals. It is also employed as a wood preservative. Because its composition can change based on humidity, copper chloride must be stored in a sealed container in a cool, dry area. It is highly toxic to humans, so gloves, goggles, and a breathing mask should be worn when handling this substance.