What is the virtue of using antimony (kohl) from a Sharia and medical perspective, and how can one ascertain its authenticity when purchasing it?

There are texts that mention the superiority of applying kohl, specifically ithmid (antimony), as it clarifies vision and promotes hair growth. Ibn al-Qayyim mentioned the benefits of kohl in general, among them preserving eye health and strengthening vision, and ithmid has a special property in this regard. As for the method of verifying its authenticity, those knowledgeable in the matter should be consulted.