Yes, yes to both @OrbitOrange and @Islandmomma. I have a number of small books that have helped me, and one is Turquoise Unearthed. I’ve been thinking about eventually purchasing some more, so I’ll have to check out Islandmomma’s choice (and see what others on here mention). I also often look at the Durango Silver website and watch YouTube vids. Sometimes I just Google a particular type of turquoise and look at what comes up. BUT I’m pretty picky when I do that as to which ones; I’m generally leery of many things on Etsy and even ebay. There are so many there that just guess or (IMO) are wrong. I like websites of legit shops (Perry Null, Garland’s, etc). I have a great book called Trading Post Guidebook by Patrick Eddington and Susan Makov which won’t help identify stones, but will tell you where are some great places to buy (and look), and has the websites of those stores.
I also completely agree with OrbitOrange in that even when you think you might know what turquoise from a particular mine should look like, then you find out it’s from somewhere else (here’s looking at you Kingman). So it ends up being an educated guess.
I would also add that, if you can, physically go to the source (the southwest or even some great museums). Seeing the stones in person makes a HUGE difference. I have learned SO much on this site, but realize that the time I’ve spent learning (often from wonderful trading posts owners) on my trips to AZ and NM gave me the base to have the feel for turquoise. But I totally know that’s not an option for all.
Have fun learning!!