The worst purity for a RC is 100%, its the very worst.
If a drug is touted as 100% pure it means your vendor is lying about the purity and if he lies about the purity he might also be lying about the drug's identity, or have an unscientific mindset which can lead to accidental mislabelling.
When I read the chemical name of a drug, before my minds eye I see the lingo translated to a molecular structure that dances and rotates around freely in space. If I see something like 1-(4-chloro-2,5-dimethoxy-phenyl)propan-2-amine I visualize the molecule and get a ton of speculative and factual information about the drug based on its structure. Thats cause I know chemistry, and because of that I would never confuse 1-(4-chloro-2,5-dimethoxy-phenyl)propan-2-amine with 1-(4-Chloro-2,5-dimethoxyphenyl)-2-ethanamine, because the structure I build in my mind doesnt match up. This is how vendors and users mistake DOC for 2CC and end up putting someone in the hospital. They dont see that extra methyl because they dont know what they're reading. That doesnt make me special, it makes me educated. And I educated myself, you can do too, now that we have the internet ignorance equates to lazyness, not lack of access to information.
Its good you came here to educate yourself.
aMT, or Alpha-MethylTryptamine, is a very hardcore drug. Some love it, others get very sick on even modest doses. For this reason do an allergy test and start low. Don't take the drug in public until you are experienced. use it pure, don't throw it in the mix with other drugs.