A flake powder. This powder used to be a favorite for 9MM decades ago, but it has fallen out of favor from better choices, namely Power Pistol and now BE-86. This powder no longer has a point for use in 9MM when you have those other 2 to choose from, but that doesn't mean its not still great for 9MM. It is. Its bulky too, as you can see, with the above pic. With Power Pistol & BE86, you can put way more powder in the case.
One downside to this is many powders look "similar" to this powder. 800X comes to mind, like dark corn flakes. If you change out powders a lot, there is a remote change you could mistake this for something else. So be careful.