Calling the police isn't going to do him any good. That's only going to make him alienated and drive a wedge between you rather than seeing him as an ally. It could be a lot of things. It could be methamphetamine, research chemicals, or MDMA, but it could also be pills that he crushed up in order to snort. There are many types of pink pills that some people crush up to snort. Various opiate pain pills come to mind, but adderall is also sometimes pink and sometimes snorted. These are the two possibilities I can think of that I've heard of/seen people doing, but as some people have said it could be some sort of very unusual and dangerous research chemical. Unlike some of the other posters, the fact that the substance was pink isn't necessarily a "very bad sign", as it could be lots of things, some much worse than others.