Sources for mixing glazes

Hey everybody, I wanna get started mixing my own glazes and just wanted to ask for a place to start, may it be a book, videos or a forum. I’d be especially interested in „natural“ glazes so using mostly very simple ingredients. Also the place I’m working at is quite remote and has their own water circuit so it’s very important that nothing environmentally harmful or toxic gets into the water. Obviously we’d be using system to avoid that in generell, but using non harmful glazes would be even better.

Its a very new topic for me so I’m excited for your help! Also I have a degree in chemistry so I’d have no problems with more complex sources.

Thank you!