Like said by others, pure heroin is white powder. This doesnt mean white colored heroin you buy somewhere is pure. Pure heroin is generally not sold to users, and is usually cut to at least some degree by the chemist after making it. If a chemist is bothering to refine it to heroin #4, they would most likely have the sense to immediately cut it, and it would without a doubt be cut again when sold by the distributer. Pure heroin on the street would be a disaster. But, there are forms of brown rocks, which turn into powder, that can sometimes be very powerfull and potent, but not pure by any means. And tar heroin comes in different colors, black, brown, and reddish, and varies greatly on consistently (some is very soft, others is very hard). In general, soft tar heroin is brownish-red and is good for smoking, and hard tar is black and meant for injection or smoking (it is rough to smoke), but there are occasional anomolies (ive seen some very soft dark black stuff, and hard brown tar).