Types of Heroin:
Most heroin is packaged and shipped in bricks of powder. Pure heroin is white, but the color when it reaches the user can vary from yellow to dark brown, owing either to impurities during the manufacturing process, the presence of powdered additives, or both.
Heroin is usually cut with baking soda, powdered milk, baby powder, sugar, starch, or quinine, but has also known to be cut with lidocaine, curry powder, strychi-nine, and even laundry detergent. Law enforcement officials in New York report the existence of heroin cut with a rat poison from Santa Domingo called Tres Pasos(meaning "three steps"). Three is the number of steps the mice take before dying after exposure to the poison.
Another form of heroin commonly distributed in the western and southwestern regions of the United States is called Black Tar or Mexican Brown. These varieties are produced in Mexico and—because they're manufactured crudely—have an either hard black coal or sticky, tar-like consistency. Purity rates range from 20–80%.
In 1980, the purity of heroin was somewhere in the 4% range. In 2002, the average bag sold by dealers in the United States was almost 40% pure, and sold for less than one-fifth the 1980 price.