Is crack cocaine man made or natural?

Hardly.

cocaine starts off with the coca leaf (which itself is natural) but it's processed much like a better version on methamphetamines. I've heard of cocaine being processed with formaldehyde, gasoline, ammonia, turpentine, etc.

the fact is, once the leaf leaves the bush and sent to process, its no longer natural.

besides, when you buy it on the streets its very rare that you're getting only cocaine. more than likely you're getting cocaine with meth, with baking soda, with baking powder, powdered sugar, detergent, anything to help dealers and suppliers turn a profit.